The flexplate that the customer ordered and bought in is the FRPP M-6375 H64. Perfect for the 8 bolt crank. Not perfect for the stock torque convertor. The bolt pattern is smaller on the stock tc and there are indentations in the new flexplate itself that you need to match up and drill the smaller hole pattern. It won't throw off any balancing because the holes are opposing. Pita and I would go with a new convertor, but, when the customer brings you all the parts and says "Here, make it work"...
Oh yeah, weird drill bit size to, something like a 29/64ths. Matched the stock holes perfectly.