i am pretty sure you are right. my 63 vette had the small bearing. jimIf you have a 62 T10, the 63 bellhousing won’t fit, the 63 only BH and T10 has a one year only small input bearing housing. You need a 168 tooth flywheel which any from 62 back will be and then you are looking at those that are internally balanced which was the case for everything up to the 454 and and 168 tooth small blocks except the 400. You can buy new aftermarket flywheels.
For a BH, you need one that fits the 168 tooth flywheel.
Are you looking for numbers matching or just something that will work?