The fittings on Dr. Diff's m/c's are SAE, you don't need to make any changes to the brake lines. They're from the later "cloud" cars if I remember right. You can buy them in 1-1/32", which is what they are originally. Cass actually sleeves them down to make the 15/16" version. And like I said, my Challenger runs 11.75" disks and 2.75" bore calipers, the 15/16" works great.
Except it's a '64 Fury. What's the pedal ratio? The original m/c in that car was a single pot with a 1" bore. There's a lot more to it than just the size of the m/c bore and the piston bore, the piston travel, pedal ratio, and size of the rear wheel cylinders are part of that too. When I converted my old '55 Dodge Coronet to a dual m/c and disk brakes I needed a 1.125" bore master, even 1-1/32" was barely enough to keep it off the floor. But that doesn't mean that all cars with disk brakes need a 1.125" m/c.
