My $0.02,
Do NOT use a smaller bore mc than original mc, you won't get a good pedal and won't be safe. When switching to dual circuit mc and staying with 4 wheel drum manual do NOT use a power brake mc (shallow hole), use a deep hole manual brake mc. I made the $50 mistake of using a smaller bore mc, it stopped the truck but did not have a good pedal / not safe. You will bleed them brakes forever thinking its air in the lines, but it too small of a bore mc. Been there did that.
