US A-bodies had 9” drums too, and they were then, and are still, pathetic.
Better braking is never a bad thing.
For the OP, I run 15/16” master cylinders on all my manual disk cars. Best of both worlds. Good feel and brake modulation without too hard of a pedal or too long of a pedal stroke.
And I have run the 15/16” master with 11.75” disks up front and 11x2.5” drums out back, as well as with DoctorDiff’s 13” cobra kit up front and 11.7” disks out back. Like I said, better braking is never a bad thing.
