What engine was originally in front of the TH400? There should have been a crank spacer on the back of the crank of the original motor, he may have missed it? I have a 360 flexplate out of a later Wag and a 360 flexplate out of a 72 and when comparing them you can see that the 72 one has a different offset so when bolted on to the back of the crank with the spacer in between it puts the ring gear teeth farther forward to engage the starter correctly and still put the torque converter far enough back to engage on the tranny. The newer style does not have this kind of offset built into it. Does he have the crank spacer, without that it wont go together correctly at all...