'63 Disc brake upgrade - studs ?

I think the factory Kelsey-Hayes disks for 64-72 used the same 7/16" diameter since the same wheels and lug nuts could be used on disk or drum. Not sure on the length. Factory 73+ wheels had 1/2" studs. Wheel studs are one of the easiest things to buy and I don't think they vary between Mopar, GM, and Ford. I would get RH threads so tire monkeys don't spin your studs. The length needed may also vary with what tires and lug nuts you use. If you plan to race, U.S. tracks usually require that the studs be long and protrude well beyond the nuts.