Actually, the baacks dont interchange very well either due to the opposite hinge points.
Is the seat bottom foam material different between the driver's and passenger's side?
Repairing your broken up foam will be difficult. Have you taken it apart yet ?My bolster areas need to be reinforced. Trying to decide the easiest route. Either build it up with some foam or make a passenger one fit. Obviously finding perfect driver's seat foam would be nice, but unlikely.