My friend that tried making his 22RE water-powered ended up putting a 4.3 Chevy with a throttlebody in it. That was a pretty good fit and wasn't a big parts breaker. Exhaust manifolds off a Chevy Astro van were used. It seems to me he was able to use the Toyota ECU too but it was @ 15 years ago I helped him do it . There were only 5-7 wires you had to hook up IIRC.
I would agree with BOGDOG though. Figure out what you want to do with it. I personally would stay with a 22RE or maybe the Benzo swap I mentioned.
I wonder if anyone has tried squeezing a WRX boxer motor in one yet.