i use a 1.032 bore master cylinder and 7/8" rear cylinders in my '65 coronet manual brakes. i couldn't tell any difference between to stock rear cylinder and the 7/8"; but master cylinder is a different story. don't use the 15/16". i done that before and it didn't work well; too much pedal travel. i would only use a 1" bore or the 1.032" bore for the master cylinder.