[Pete F]

I put a dual master on my 34.
The important question is what diameter master are you taking out.
If the diameter is smaller it will take more pedal travel to push the same a mount of fluid to stop the car so diameter is a big fact.
Second I put residual valves is both lines at the master to hold the fluid on the wheel cylinders so the pedal is always firm.
Third the hole closest to the mounting flange is internally valves for the front brakes
Good Luck