There's the proper way, then there's the cheap way.
My recommendation is the proper way, drop an STi engine in there. It will fit fine, all engines will. But you will have to reloom the car which will be a lethally painful job. Bolting a turbo to a tired old N/A is one very quick way of destroying an engine.. then you're s**t outa luck. Best of luck to him, it's one of those things i love seeing people do, giving those old legacy's the power they were designed for! (if you didn't know, in japan they come factory with twin turbo's, and 270 crank HP)