It'd be interesting, but I'd expect quite a bit of work getting that FWD engine to mate up. If you do it, keep us informed on the work with lots of pictures! As cheap as those engines are and how easy the engine and tranny come out of the GT6's and Spits, it might be fun to have a 65mpg conversation piece!
If you're after not quite as much effort, there's a lot of aftermarket for the 1.8L Miata engines, and transmissions are super available (used in all the B series trucks, and some Rx7s, also.) Harder to find, but a BIT more technically accurate, there are some rear wheel drive nice Ford Engines (like the Ecotec, but with a different transmission bolt pattern, I guess?). It's the weapon of choice for the Caterham 7 clones, because there's a lot of neat work with these engines in Britain, but not much makes it's way across the pond.