Those are cool little kits. I stocked up on all of 'em years ago when they were very cheap.
I'm sure you've realized they're down around 1/32 scale, unless you opt to build one of the micro streamliners like Pumpkin Seed.
I started a similar project, and realized almost every major dimension would need to be enlarged to get most any kind of V8, driveline, and a scale pilot in it.