Yep, you're on the right track now. The plans should have a view looking down that should also identify the location of the sliding hatch and doors, the engine hatch and the skylight.
The Pride of Baltimore 2 website should have more deck pictures. That, or a web search will help.
And you're correct on the bow. The samson post dictates the bowsprit and windlass location.
Regarding the samson post chamfers, here's an idea (I haven't tried it, so I don't know if it will work). On full size chamfers, we mark a line a certain distance from the edge, but parallel to the edge. You should be able to duplicate it using a .5mm mechanical pencil. Extend the lead to the width you want on top and draw with the side of the lead on the top of the post. You should get a shaded rectangle on the top. Do the same on each side(extend the lead for how far down as you want the chamfer to go and use the side of the lead again) and remove the shaded areas (probably with sandpaper). You might also consider using something harder than basswood for the samson post. Basswood is easy to work with, but it gets soft and fuzzy. Try a piece of cherry cut to the same dimensions and you may have better luck.
But your existing samson post looks pretty good to me.