Starter problem

I have an 81 Cutlass and I just recently dropped a 350 out of a '70 Chevelle/Malibu into it. Bought a high torque mini-starter and installed it into the car, started up nice the first time around, then the drive went, replaced the drive and put it back in the car and now it sounds like the gear is jamming on the flexplate, so I tried shimming it to see if that made any difference, it didn't. The flexplate isn't warped or cracked or anything like that and the starter calls for the right amount of teeth. Any suggestions on what to do? Help me out guys!


Thanks a lot
-Sean