The one that I saw used a D- or B-series. What they did was one way or another put the front hubs on the rear so the stock drivetrain would remain intact. For all the engine knew, it was still pulling the car versus pushing it.
Easier said than done, but all that needs to be done is cut the floor pan, fabricate some mounts, some rerouting of fuel, coolant, and wiring, and intake and exhaust. How hard can it be? Who knows, I may get half-way through the conversion and end up with a for sale post.
This car has been through a lot. It started as an STD. It got an SI cam, SI ECU, complete CRX dash, rear disc conversion, SI diff, full exhaust, and ITBs from an '01 CBR 929RR. RWD seems like the next logical step. Why not take it?