The Torque converter pilots on the the crankshaft. That said the location of the holes in the flexplate is not as critical since the dont center the converter. They do have to line up so you can get the bolts in and be accurate located so that they load up on the converter bolts evenly when transmitting torque.

Also the term for the part that I would use is flexplate.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...