Numerous solutions here, but if you choose to stay with the original Budd set up, Dura Brake makes the rotors still, I believe. They DO still turn upon eBay from time to time, but investigate first. For the pads, make sure you find D-10, not widely available, but they ARE still out there. Calipersonline probably still has the calipers, but read up on the reviews, as they seem to be mixed.
If you go with something from a later C-body, Murray Park probably has EVERYTHING you need, and knows which items you do and don't need........