Jud, I'm a vistor-browser here (not a modelbuilder), but I've used a radial saw for many years, and there are a few things that I would suggest.
1. The best saws that you could find are from the late 1950s era DeWalts - MBF, or 925, which are 9" saws. Saws from later years are not so well-built.
2. The saw must be aligned, and the most important alignment is eliminating blade heel. By this, I mean that the plane of the sawblade is perfectly parallel to the trackarm.
3. The choice of sawblades is very important. Do >not< use a tablesaw ripping blade. I favor a thin-kerf 8-1/2" blade for a sliding miter saw with a negative hook angle, or maybe up to +5d. Generally, positive hook angles are too aggressive and can be dangerous.
4. The biggest problem I see, is holding the stock for cutting. It's not a good idea to place the end of a narrow board against the fence for ripping. I would make up a larger board (at least 12" square) to hold it, and would probably attach it with woodturners doublesided tape. Then, I would not cut completely through the stock. Assuming that you're using 3/4 stock, set the depth at 11/16", thus leaving a 1/16" web. Then I would split the pieces off and clean them up with a block or violin plane.
5. You might get some ideas here, from something I posted about 10 years: http://www.mimf.com/old-lib/hammond_radialarmsaw_jigs.htm