Don't panic!.. now this an easy one.. the car was built and optioned to take both.. you'll need the engine and trans, the engine mounts from a donor car, in fact if you can get the engine(complete)/trans/ gbox crossmember (although they are usually the same piece, they just need to be moved to the either forward or rear factory holes that will be there) starter, radiator the swap will be fairly painless..depending on which box was in the car if you fit a C4 with the V8 even the tailshaft will fit.. the 4 speed will take a bit more but if you can get to see a similar optioned car from underneath the swap becomes more understandable..buy a small dose of patience and it will all fall into place.. Mr Ford didn't build the cars on the assembly line having to to have a lot of differing components to acccept the different drive trains in these cars..
Contact the Fairlane Club of America and a member or two will step you through it, they a re a great bunch of people...
http://fca.clubexpress.com/content.a...club_id=363066