I did it the other way around. 22R to 22RE Seemed like a big improvement to me. Also seemed simpler than messing around with all those hoses and vacuum valves that the carbed motor has. I hear you can strip down a 22r to make it pretty simple, but the factory set-up in my '84 22R w/California emissions was complex.

For your case though it comes down to wiring and fuel. You can leave the electric efi fuel pump in your tank and use a regulator to lower the fuel pressure or you can use the engine mounted mechanical fuel pump to pull fuel through the disabled electric (in-tank) fuel pump.

As far as the wiring goes I don't know if you can use the 22RE wiring and computer to run a 22RE distributor and ignitor in your 22R motor. Although it seems like the computer would freak out with out a throttle position sensor signal and a air flow signal. You probably would need to do a complete wiring harness swap. -- Matt