I have an important question... Did your Squarebird come with a power brake booster mounted in the engine compartment?
Dkheld knows his stuff. He is using a Granada setup (and so am I, on our '55 Customline). For fifteen bucks, I had a lathe hand turn down my rotor snouts to match my OEM hubs. Both the Granada and the S-10 systems work equally as well.
I'm also using the Scarebird (S-10) setup on our '59. I don't have a preference because I was able to get the Granada setup cheap, from a bone yard in Florida. They both use a 2.5" piston on 11" rotors, so they stop about the same.
What wire wheels are you running? - Dave