Not sure what "blew out" means for an MC, but sounds like it wasn't Tuff enough. No excuse for an MC seal blowing or whatever, even if you are an NFL linebacker. I recall 1"D bore is standard for power brakes on my 65 Newport, but check rockauto. A larger bore will require more pedal effort, but less travel. I wouldn't go larger. When the booster on mine failed (w/ factory single pot MC), I rolled thru a stop sign trying to stop w/ both feet, like trying to stop a train. I now have a new booster w/ 7/8" D bore dual MC (for 95-99 Breeze/Cirrus/Stratus w/ ABS). It stops almost too easy w/ the booster, but should be manageable if another booster failure. Mine has all drums, so can't imagine stopping a front disk car w/ failed booster.
If you put a 2-4 bolt Mopar adapter plate on your booster ($30 ebay), you can mount many later 2 bolt MC's. I recall the Bendix booster I have now has an adjustable tip to match for the MC. I kind of recall that also on the earlier Midland-Ross booster I had. I chose the Breeze MC just because I was using it on my 65 Dart and 64 Valiant too (consolidates parts). You might not need to adjust the booster tip since my Valiant is manual brakes and I found that w/ adapter plate, the brake rod hole ends up in exactly the same place as w/ the original MC. Many A-body guys use a 2-bolt MC for an 80's Dodge truck. Dr. Diff sells w/ adapter for $95, but you might want the custom 15/16" bore upgrade for $125. I wouldn't use an earlier cast-iron 4-bolt MC because they have leaky lids which not only sloshes out DOT 4 "paint remover", it similarly lets moisture in (corrosion), though I use DOT 5 (silicone) fluid. They also get rust ugly, though some value that "original look". Not true that you can't use a drum-drum MC. Only difference is the disk/drum MC's have a larger F reservoir, but if you keep on eye on fluid levels a drum-drum works too. There is sometimes a "residual valve" in a drum MC port that needs removing so no pressure lockup (dragging calipers), and I hope you installed an adjustable proportioning valve in the rear circuit so you don't lock-up the rears first and spin-out on turns.
