Nice. That would solve the issue.
I would suggest if someone went down the road of using Mustang brakes, I would try and find adapter plates that allow the GT350 calipers to be used on the S197 knuckle for the 4 piston calipers, and then setup the A-Body to match those S197 mounting lugs. This would allow (in theory) for the same lugs to mount a 14"/4 piston setup, a 15"(S197)/6 piston (S550) setup and a GT350 caliper with whatever rotor the adapter was built for.
I would not use the S550 mounting lug locations though as the 14"/4 piston setup is junk and would mean the only good options would 15"/6P and the above GT350 caliper kit. And any aftermarket kit that was available, but generally those are $$$.