Jaager

That sort of puzzle is one of the brain activating parts of all of this.
Think about it when trying to go to sleep - you may wake up with an answer.
Take a step back and imagine the sort of structure needed to hold the parts in place.  Sometimes, this support structure is as much as 90% of the whole.
Construct jigs with screws and ways that can be taken apart - so that the parts can go into a scrap box to be reused for a later project. 

From your picture, it looks like the plans have full size patterns for every component.
It may require use of a steam iron first, but you could scan the patterns, adjust for the built in scanner aberration, and print them out for a redo.
Using something better than Lime  gives a bit joy to work with - but I advise avoiding any roll cut veneer.
 

I tried about every organic solvent available to civilians.  Several will denature it.  Nothing will wash it off.  I searched the MDF for the solvent in the can.  It seems to be a mixture that you really don't want to know is in it and still be willing to be in the room with.
I seem to remember that rubber is one of those polymers that has no practical solvent.  I remember an old saw about a way to get rich was to find a solvent for Cellophane% - perhaps rubber and synthetic rubber are the same?  Some chains are probably just too long.
 
% I was born and raised in Richmond where and when the manufacture and sale of packs of lung cancer and COPD was a major industry.  So too was the manufacture of tetraethyl lead.

No, I have not.  I bought a large green and a large blue single tile from Home Depot in the late 90's for the heck of it.  I do not remember to price being all that prohibitive.
It is just another armchair thought experiment.

Isopropyl alcohol - the 91% first aid stuff - will debond PVA and alcohol does not swell the wood and dries fairly quickly.
PVA is not sensitive to acetone,  but the hated CA is.  Duco nitrocellulose is.
Hide glue is completely denatured by hot ethanol.
I use Titebond II (a yellow PVA) - with is water resistant - because we live on a water planet.  Titebond III ( an amber PVA) is waterproof.
 
A flat board wider and longer than the dory.
Draw a center line the length of the board,
A block of wood about 1/4" thick -  cut one end at the same angle as the slope of the transom.
A couple of holes - counter sunk under the base board and drilled thru the block can be used for threaded bolts to hold the transom support block - If the holes are a tad larger in diameter than the bolts, there will be some play to allow adjustment to square before the washered wingnuts tighten it to the baseboard.
 
Fix it to the base at one end.  The slope and flat edge of the block will support the transom at the angle cut and if mounted correctly square to the midline.
A similar block can be cut to match the stem and fix it square.
 
I would use Dritz 3009 1 3/4" quilting pins - at #70 hole is tight enough, but does not freeze the pin.   A bamboo trunnel can fill the holes or a brass pin - do not leave the steel pins in the model - they will rust,
 
Outboard blocks can be placed outside the dory body at each rib location . if placed square a wood strip connecting them will hold each rib perpendicular and vertical.
 
Once all that is setup and bonded the fore and aft blocks can be removed and the side blocks used to secure the inverted hull.
 
Use a curling iron - a rheostat may control the heat - to bend the planking - only heat is needed - water just swells the wood and it does not return the wood to its greenwood state - Prebending allows for an easier glue bond - no resisting forces.
 
With a jig this involved, you can go into the mass produced dory model business. 
 
If you know the dimensions of any future models, the baseboard can be cut large enough for their use.

Isopropyl alcohol - the 91% first aid stuff - will debond PVA and alcohol does not swell the wood and dries fairly quickly.
PVA is not sensitive to acetone,  but the hated CA is.  Duco nitrocellulose is.
Hide glue is completely denatured by hot ethanol.
I use Titebond II (a yellow PVA) - with is water resistant - because we live on a water planet.  Titebond III ( an amber PVA) is waterproof.
 
A flat board wider and longer than the dory.
Draw a center line the length of the board,
A block of wood about 1/4" thick -  cut one end at the same angle as the slope of the transom.
A couple of holes - counter sunk under the base board and drilled thru the block can be used for threaded bolts to hold the transom support block - If the holes are a tad larger in diameter than the bolts, there will be some play to allow adjustment to square before the washered wingnuts tighten it to the baseboard.
 
Fix it to the base at one end.  The slope and flat edge of the block will support the transom at the angle cut and if mounted correctly square to the midline.
A similar block can be cut to match the stem and fix it square.
 
I would use Dritz 3009 1 3/4" quilting pins - at #70 hole is tight enough, but does not freeze the pin.   A bamboo trunnel can fill the holes or a brass pin - do not leave the steel pins in the model - they will rust,
 
Outboard blocks can be placed outside the dory body at each rib location . if placed square a wood strip connecting them will hold each rib perpendicular and vertical.
 
Once all that is setup and bonded the fore and aft blocks can be removed and the side blocks used to secure the inverted hull.
 
Use a curling iron - a rheostat may control the heat - to bend the planking - only heat is needed - water just swells the wood and it does not return the wood to its greenwood state - Prebending allows for an easier glue bond - no resisting forces.
 
With a jig this involved, you can go into the mass produced dory model business. 
 
If you know the dimensions of any future models, the baseboard can be cut large enough for their use.

No, I have not.  I bought a large green and a large blue single tile from Home Depot in the late 90's for the heck of it.  I do not remember to price being all that prohibitive.
It is just another armchair thought experiment.

I have been imagining using sea green or blue marble tile as a base.  It does increase the weight significantly, but it sure ain't going to tip over very easily.
It would be a chance to use the diamond hole boring bits from American Surplus.
 
A dark Rosewood dye on the frame?

I have been imagining using sea green or blue marble tile as a base.  It does increase the weight significantly, but it sure ain't going to tip over very easily.
It would be a chance to use the diamond hole boring bits from American Surplus.
 
A dark Rosewood dye on the frame?

If it is similar to DAP Weldwood contact cement  it is a synthetic rubber.
It is for adhering plastic laminate to a base. 
The layer is thick - too thick for scale - and it is prone to oxidizing after a decade or two = brittle and a release of the bond.
 
"You don't want it."

I tried about every organic solvent available to civilians.  Several will denature it.  Nothing will wash it off.  I searched the MDF for the solvent in the can.  It seems to be a mixture that you really don't want to know is in it and still be willing to be in the room with.
I seem to remember that rubber is one of those polymers that has no practical solvent.  I remember an old saw about a way to get rich was to find a solvent for Cellophane% - perhaps rubber and synthetic rubber are the same?  Some chains are probably just too long.
 
% I was born and raised in Richmond where and when the manufacture and sale of packs of lung cancer and COPD was a major industry.  So too was the manufacture of tetraethyl lead.

DAP Weldwood is very thick and amber.  Applied from a tube, I think that the bore of the tip would need to be fairly large and would need strong thumb muscles to extrude it.  I use it to hold sandpaper to a Maple sanding drum.  Mineral spirits will cause it to roll into balls, but I have found no actual solvent to remove it.  So, replacing the sandpaper is a major project. 
 
Clear and gel sounds like nitrocellulose in acetone - reasonable prise hold strength, but like CA,  leaves a bit to be desired holding against a sheer force.

If it is similar to DAP Weldwood contact cement  it is a synthetic rubber.
It is for adhering plastic laminate to a base. 
The layer is thick - too thick for scale - and it is prone to oxidizing after a decade or two = brittle and a release of the bond.
 
"You don't want it."

That sort of puzzle is one of the brain activating parts of all of this.
Think about it when trying to go to sleep - you may wake up with an answer.
Take a step back and imagine the sort of structure needed to hold the parts in place.  Sometimes, this support structure is as much as 90% of the whole.
Construct jigs with screws and ways that can be taken apart - so that the parts can go into a scrap box to be reused for a later project. 

From your picture, it looks like the plans have full size patterns for every component.
It may require use of a steam iron first, but you could scan the patterns, adjust for the built in scanner aberration, and print them out for a redo.
Using something better than Lime  gives a bit joy to work with - but I advise avoiding any roll cut veneer.
 

If it is similar to DAP Weldwood contact cement  it is a synthetic rubber.
It is for adhering plastic laminate to a base. 
The layer is thick - too thick for scale - and it is prone to oxidizing after a decade or two = brittle and a release of the bond.
 
"You don't want it."

DAP Weldwood is very thick and amber.  Applied from a tube, I think that the bore of the tip would need to be fairly large and would need strong thumb muscles to extrude it.  I use it to hold sandpaper to a Maple sanding drum.  Mineral spirits will cause it to roll into balls, but I have found no actual solvent to remove it.  So, replacing the sandpaper is a major project. 
 
Clear and gel sounds like nitrocellulose in acetone - reasonable prise hold strength, but like CA,  leaves a bit to be desired holding against a sheer force.

If it is similar to DAP Weldwood contact cement  it is a synthetic rubber.
It is for adhering plastic laminate to a base. 
The layer is thick - too thick for scale - and it is prone to oxidizing after a decade or two = brittle and a release of the bond.
 
"You don't want it."

The Wood Database translated to relevant
the wood is hard
it is essentially interchanged with Hickory - which means that it is open pore. The grain and pores do not scale well.  Sealed and painted or hidden, it should do as well as Hickory, Ash, Oak, Walnut.  It is apparently tricky to mill - tearout or burn if tool edges are not really sharp.  
 
If it were Apple or other fruitwood you would want to kill for it.  Nutwood is better for 1:1 scale projects.
If you seal the ends well, debark, protect from rain, give it good airflow, when seasoned  -1 year per inch - you will have a good utility wood - jigs - inside the hull parts.
I can get other nutwood - Oak, Walnut, Ash - already seasoned and in rectangular form from Yukon Lumber right now. 
It is not trash, (anything in the Cottonwood family is trash),  but for a one off, learning to mill, not going to expand to other really desirable and otherwise unobtainable species,  the specific reward from this log will be relatively low.  I would probably process it and try to make something unique from a small fraction of it as a gift to the neighbor.  Now, if you have neighbors with Apple trees, Plum, Crab Apple, Japanese Plum (Loquat), Hawtorn, Dogwood,  possibly Peach if you can beat the fungus,  and given the prices Holly - for us less than snow white and even Blue Mold infected Holly is right at the top of desirable - -- bribe them -  be a wood vampire.

Way back when, I bought a Unimat SL.  Primarily because it was as close as I could come to getting something like Longridge's Midget Universal machine. 
It was for the woodworking aspect rather than the lathe.   At the time, there were essentially no stand alone model scale machines.  I burned out a motor
using the Unimat as a tablesaw.   (I also bought an Emco Maier BS3 - a large benchtop 3 wheel bandsaw. - It was a well made machine, but any 3 wheel bandsaw is based on an absolutely terrible design.  A perfect machine would still be awful to use.) 
 
The Unimat was pretty good at being a small under powered tablesaw, drill press, saber saw, disk sander, etc   At the time, there was little or no competition.  NOW, 
The Byrnes saw is at least 10 times more capable at its function.  There are a variety of mills and drill press machines.  A Rikon 10" bandsaw is a better jig/saber type scroll sawing machine.  I would not advise using it for heavy duty resawing though.  Byrnes has two models of disk sanders that are much better at that job.  There are more capable  small lathes.  The Unimat was great for its time.  Now,  it has been supplanted.  It had inspired competition from stand alone single purpose machines that were better at doing their portion of each of its functions.   As for a lathe and spar shaping -  a major negative is that the actual spars were shaped by cutting along the grain.  A lathe cuts across the grain.

Way back when, I bought a Unimat SL.  Primarily because it was as close as I could come to getting something like Longridge's Midget Universal machine. 
It was for the woodworking aspect rather than the lathe.   At the time, there were essentially no stand alone model scale machines.  I burned out a motor
using the Unimat as a tablesaw.   (I also bought an Emco Maier BS3 - a large benchtop 3 wheel bandsaw. - It was a well made machine, but any 3 wheel bandsaw is based on an absolutely terrible design.  A perfect machine would still be awful to use.) 
 
The Unimat was pretty good at being a small under powered tablesaw, drill press, saber saw, disk sander, etc   At the time, there was little or no competition.  NOW, 
The Byrnes saw is at least 10 times more capable at its function.  There are a variety of mills and drill press machines.  A Rikon 10" bandsaw is a better jig/saber type scroll sawing machine.  I would not advise using it for heavy duty resawing though.  Byrnes has two models of disk sanders that are much better at that job.  There are more capable  small lathes.  The Unimat was great for its time.  Now,  it has been supplanted.  It had inspired competition from stand alone single purpose machines that were better at doing their portion of each of its functions.   As for a lathe and spar shaping -  a major negative is that the actual spars were shaped by cutting along the grain.  A lathe cuts across the grain.

It looks like the General pin vise that I bought when I started all this -  the early "70's.  It was/is better quality than the now stuff, the collets = two units - different bore at each end - there is a storage cavity at the swivel end. 
Still my go to- mostly. 
I have never been introduced to the Starrett version.  A four unit set would probably be worth it if the buyer was young.

I have a Unimat SL 1000 lathe (sold as the Unimat DB in Europe) which I use for turning and milling small jobs in metal, wood, and plastics. The Unimat SL/DB model has a post to which the motor and headstock are attached to turn it into a milling machine. There are several accessory attachments including a screw-cutting attachment, a table saw with about a 6" by 7" table, a wood planer, a wood router, a fret saw (scroll saw,) and a jig saw (sabre saw,) together with a full range of all the standard lathe and milling machine tooling. Emco in Austria made them beginning in the early 1950's until 1977. The SL/DB model was then replaced with the slightly larger Unimat 3 which ceased production in 1990,  There are many Unimat lathes in circulation and they now enjoy something of a cult following in the model engineering field even though the machines, motors, attachments, and tooling can only be sourced on the second-hand market in most every instance and notwithstanding the fact that the Sherline and Taig lathes and milling machines and even the ubiquitous Chinese Sieg "7 by's" are readily available and offer some advantages over the older Unimats.
 
The Unimats are finely finished machines capable of relatively fine tolerances as might be expected of post-war Austrian machine tools. Consequently, they were never inexpensive machines and today on the used market they continue to increase in cost, eBay being the main marketplace for all things Unimat. (Prices seem to be lower in Europe than in the US, apparently because there are more of them in circulation over there.) Today, the accessories and tooling are less commonly available than the basic machines, which seem to have been bought and used little more often than the accessories. As with any lathe or milling machine, one should budget at least as much again for the tooling as for the basic machine. 
 
At present on eBay, a basic "user" Unimat DB/SL lathe in decent shape starts at around $500 and can easily approach $2,000 for a "mint" example in the original fitted storage case. Worn out rusty abused examples can be had for a bit less, but the cost of parts to bring them up to snuff may well exceed the price of one in good condition at a higher price. The tooling, so much of which is unique to the Unimat, is exceptionally expensive. (A Unimat collet chuck and a set of collets sells for just over $1,000... when they can be found.) There are presently Unimat table saw attachments on eBay listed at between $225 and $275. (And some incomplete ones for less, but good luck trying to find the missing part or parts essential to making the thing work!) 
 
So, if you know somebody whose widow has a Unimat and a lot of attachments and tooling down in the basement that she wants to get rid of cheap, grab it, but if what you really want is a table saw, you will likely pay half again, if not twice, what a new Byrnes table saw would cost you to possess a working Unimat with the table saw attachment which can't hold a candle to the Byrnes table saw because the Unimat was designed to be a lathe, not a table saw and the Byrnes saw is a table saw and nothing else.
 
See: http://www.lathes.co.uk/unimat/ for detailed information on DB2000 and SL1000 Unimat lathes.
See: http://www.lathes.co.uk/unimat/page2.html for information on Unimat accessories
 
 

Sprue Brothers  has been a source:
 
https://spruebrothers.com/tools-supplies/tools-cutting/?page=1&mode=6

Sprue Brothers  has been a source:
 
https://spruebrothers.com/tools-supplies/tools-cutting/?page=1&mode=6