Hello all.possible silly questions not sure. I'm planning an update of the master cylinder to a dual unit.i have a 49 gmc 1-ton with stock drums.original master was 1-1/4 bore. First I've. Been searching out replacements and found a raybestos with a 1-5/16 bore would the 1/16th difference be ok to use. And secondly.what I'm seeing is two different ends on the cylinder piston where the pedal rod meets. One is a "shallow" end and the other a deeper cup where the rod goes in further. Would either work? Thanks for any help. Also as a side note. Truck never hauls any weight. Just mainly low speeds 40-50 mph. Maybe go with 1-1/8 bore? Will put on residual valves

1949 gmc 1-ton