PirateJack has a front (and rear) disc conversion that uses all new components and let's you keep 5 on 4, and 14"wheels.
I have not used any of his stuff personally.
PirateJack is just a ‘73+ disk brake conversion with the rotors drilled for 5x4” and the hub turned down a little bit. The hub may still not fit into the hub bore on the original SBP rallye’s.
DoctorDiff sells this same kit now, except you’ll get much better quality parts and actual customer service.