The rotary is a lot of fun! Don't run scared from your project due to cost! Nothing is cheap. Doing a piston engine is cheaper if you use sub-standard parts, but to do a proper build would cost more than a rotary. Take for instance my 4AGE. Head gasket, 140 bucks. Pistons, 600 bucks. Connecting rods, 700 bucks. parts and labor for the cylinder head @1800 bucks. Machine work and balancing another 450 bucks. other bits and pieces run another $1,000 or so. Just to build an engine that puts out about 150-160 hp, $4,000-$5,000??? Go ahead, put that into your rotary! Maybe a turbo? You can do some great things with that RX7!! And if you want to have a stand alone EFI but can't afford one, Greddy e-manage is not too far off. The e-manage can be bypassed, or set to a defaul setting to get by smog. Naw, don't shy away from the rotary!! Hell, if you want to talk expensive! look at the Scoot 4 rotor engine! I think you could have one for like $20,000! Output is somewhere in the 600-700 hp range! As for the smogging of the thing, it has twice the rotors, have them smog it twice!