Single piston calipers with pins are definitely a big bolt pattern set up, and work with the 73+ spindles. The pin style were typically B/E body calipers, although some of the FMJ car models had them as well. Those are the larger 2.75” piston calipers too, little extra stopping power compared to the ‘73-75 A body calipers that had 2.6” calipers.
Anyway, for rims and tires that means you have the later 73+ track width. So with a 15x7 and 4.25” of backspace a 225/60/15 is about as wide as you can go. I’m not a Barracuda guy specifically, but I would be cautious with the 215/65/15. The wider track will put those wheels pretty far out, so that lower front corner could be an issue with those being 26” tall.
