I'm currently running the B-body spindles/Hotchkis arms (they sell a bump-stop bracket that bolts to the ball joint mounting holes, made my own instead) and 12" discs on my '64 Tempest. I was running a set of 15X7" Rallye II wheels on the car before switching to a set of 17X8" steel wheels.
The '78 Bonnie that I robbed the spindles from had 15X7" steel wheels from the factory. Don't worry the 15" Rallyes will fit, I know for a fact since I drove my car after the 12" disc conversion on a set. The car has over 25K on it since the conversion, upper arms are holding up great and the car stops like crazy.
When I did the disc conversion I used a second-gen F-body master and prop valve. I bent up my own lines from pre-made lengths that you can buy at any local auto parts store. Did a disc conversion on my '64 Lemans convert as well, used '69 GP spindles/11" discs as well as the same master/prop valve that I did on the Tempest.
