Yup, the later brakes add 3/4" per side.
You'll either need more backspace on your front wheels or a shorter tire.
Since it just barely nicks the fender at full lock, you could also try adding some fender braces (or extending your existing ones) to push the lower edge out another 1/2" or so- some A bodies had them, some didn't. I don't believe the Barracudas did.
I just needed to confirm the 73 and up was 3/4" on each side wider, and if I use a pre 72 spindle with Willwood brake conversion if that would bring them back in. 3/4" should give me more than enough room.
Modifying the fenders any more than I have is not an option, honestly I don't care for the overbite look from the wide track width in the front vs the rear. I had 26" tall tires before but the Mustang wheels have 5.75 backspacing , more of a modern flat faced wheel than what is supposed to be on this car. I just drove to Chicago to pickup a set of 72 and older drum spindles so hopefully this cures the problem.