Crazy Kiwis have stuck Mini Cooper S 1275cc FWD units in them , so there is no reason why the whole drivetrain from a Honda Prelude or similar couldnt be grafted in the back end. Just depends on how much cutting you want to do, having had Hillman Imps with a Ford out the back, I can say that it will be a lot more user friendly with the motor in front of the rear axle. Another good one would be a Subaru 4 or 6 cyl motor/transaxle assy- nice low profile. Time to fire up the plasma cutter!!
