I have a set of dog dish Pontiac wheels on a set of 15x6 steelies that I kept after selling off a '78 Bonneville.
Ran them with disc brakes and no issues for several years on my '68. I wanted a wider wheel in back and ordered a pair of Wheel Vintiques and I never could get the original caps mounted on the aftermarket wheels. Wound up returning them and going with Torque Thrust mags. Still have the GM wheels and caps in my basement.
I know this has little to do with a '63 model, just saying, I had issues with OEM caps on aftermarket wheels but none at all fitting the caps on a 1978 B-body OEM wheel.
