ok i have done the conversion in to an 87 celica. Since it is already FWD then there is a good start. As for the rest, i would only be guessing. As u would have to change so much, it would probally be cheaper to find an ST165, same as the 88 celica that u have seen, but it would be 4WD.
I would have to say not to do this conversion unless u are willing to spend alot of money, have alot of time and u really want to keep the prelude body.
To start off u would have to strip the wiring harness back to individual wires and put it back together. The cross member would have to be modified(either one doesn't really matter). All the engine mounts would have to be moved to suit the engine. And so on.
If u still want to go ahead with the conversion, i have lots of info about putting it into a Gen 4 celica. Its only info so its free.