Thaught I'd ask, more on my uncle's behalf, nut is there a way of running a dual bowl master with the stock booster, or what? It really looks like your options are limited because of that crossmember going over it. What are your takes on this?
Try bolting up a 72 Mustang duel master cylinder (Drum-Drum) setup. I did this in one of my 64 T-birds. You need to make sure that the brake booster rod is long enough to engage both bowls in the master cylinder. I had to add a brake switch to the master cylinder via a brass "T" from the front brake line. I had to use a 66 T-bird cross brace to clear the mastercylinder. You might have to buy a used 64 Galaxie brace and modify it to clear the MC.
Thunderbirds, 64's, 57,2002