63 Valiant disc brake swap kits?

Any A-body disc brake kit should fit your '63 Valiant. I assume you have the stock 9" drum brakes with 13 X 4" wheels, so, you'll have to decide which kit to get and what wheels you want to use, as the 13's won't work. I also don't like the 9" brake spindles as those have tiny wheel bearings that just don't hold up all that well, therefor I'd recommend a spindle upgrade too.