Fitting an FWD engine into a RWD car usually involves some pretty techical fabrication. You have to get the engine to mate up to a transmission of some sort. This means modifying or fabricating a bellhousing that will hold the two at a proper distance, finding a pilot bearing that works with the crank and input shaft, and getting a clutch disc that will work with the engine's pressure plate. Once that complicated task is done you still have all the work left of putting a strange RWD drivetrain into a car - fabricating motor mounts, finagling clearance problems, plumbing and wiring connections, and perhaps a custom made driveshaft.

Its been done before, however. In particular I've seen VW's really neat VR6 engine in RWD applications. And I ---think--- all the current small car VW engines share a common engine to bellhousing bolt pattern - so perhaps there are bellhousings available out there? You might try looking for a VR6 part. Double check on a VW board first to see if anyone knows for sure if the bolt patterns are the same.