1966 dual master cylinder

Large bore MC will require less braking effort from the driver.
FYI, the difference between drum and disc brake MC's is the residual pressure valves. The valves were 10 psi for drums and 2 psi for discs. The older style wheel cylinders for drums required this in order to keep them in position for use. A long time ago they began to put springs into the wheel cylinders, so the residual pressure valves became superfluous. If you have the original wheel cylinders in the car the valves are necessary. The proportioning valves were to keep the rear drums from locking up before the front discs. In a non-hybrid system they are not necessary. There is also a metering valve or hold-off valve on some hybrid (drum/disc) systems to keep the front discs from deploying until enough pressure builds up to engage the rear drums- a good idea for getting all four wheels to contribute to braking.