Brake swap caliper question

Before you get too far, measure the diameter of the pistons. There are two different piston sizes for that style of caliper, the 73-76 A-bodies used a 2.6" piston, the B/E/R and all the F/M/J cars used one with a 2.75" piston. You wouldn't want to mix piston sizes on the same car. Otherwise, it shouldn't matter as long as you can find the right hoses.

And you can get calipers at any parts store or on RockAuto, they're readily available in both piston sizes.