How do u convert from small bolt pattern to big bolt lug pattern wheel
They
did have drum brake A bodies up through the end in 76, usually six or 'teen cars. Oddly, they kept the 4" bolt circle for the 4 wheel drums. No reason to keep drums when disc is so much better and safer. 73-76 A body disc cars are getting hard to find. The F-M-J cars with disc are a good source, despite the spindle being about 3/8" taller.
Scarebird make a kit that uses the drum spindle.
Mopar I believe there are other mfg that may do something similar. Then there's still the rear. Good suggestions above. Is your car still a six?