I've considered the same thing. The crossflow head design of the B21/B23/B230 family is inherently more efficient. Port designs are som what less restrictive an there is certainly no 180 degree turn in the the gas flow.

As for tuneabilty. There seems to be a lot of tuning experience out there for the OHC engines.

As for noise, I have owned both and I think the OHC motor is quieter but the difference is probably negligible.

Looks like a number of people have done the OHC installation in Amazons. The one thing I have been turned off by, is the difficulty of getting a good intake that will clear the brake master cylinder installation.. especially if mounted upright and I have found no manifold out there for that at all for that.

Some installs are really slick and go like a bat out of hell. Others are simply cobbled up messes. From experience, (V8 Vega swap) engine swaps are a PITA. They always require time, patience, money (lots), and excellent fabrication skills (often beyond our current abilities) to get a succesfull result.

I suppose something like an injected B230FT (I believe that is what it is) would fit ok but then the issue of installing the EFI hardware rears its ugly head.

There is a video out there somewhere of an Amazon with a really, really, clean turbo 230 blazing down the freeway at the speed of heat up to 230 KPH that really jazzes me. Beautiful install and obviously doe by a person with professional skills.

FWIW, if it is performance you want, bang for buck, I would go with one of John Parker's supercharger setups on a properly setup B20 and a T5 5 speed tranny. I have seen hp numbers as high as 250. No turbo lag either!!!1