1972 Front Disc Brake Conversion

A couple factors will change the braking characteristics. First is like you mentioned is the size of the cylinder. Second If you change the weight distribution, you can increase the “work” the rears have to do. (Move the battery to the trunk and lighten the front)You can also leave the adjustment on the drums a little looser. As old as these cars are there are only a couple of brake compounds available so we can’t change the compound.
I advise not to use the 2 1/2 rear brake on 72 and earlier cars. Every article I’ve found from when the cars were new (68 and up)was that they already had too much rear brake. The 2 1/2 brakes were used on later cars as the weight of the Abody increased.
Unfortunately there are only two wheel cylinder sizes 7/8 and 15/16. This doesn’t give much to work with. The Dorman 7/8 bore wheel cyl pn is W 37236.
But I don’t want to completely hijack the thread. OP was asking about a brake conversion. I’ll be glad to discuss more in a new thread