I got discs on my 37 using the the Mustang dual master cylinder.Both chambers on the cylinder are the same size on mine and the chamber closest to the mounting flange is supposed to go the the front brakes. The speed shop where I bought it gave me two special flare nuts to screw into the cylinder, using 3/16 lines front and rear.Some master cylinders have the residual valves built in for the drum brakes.I have read and been told by the street rodders that residual valves on disc brakes are only necessary if the master is below the height of the caliper.Actually disc brakes will work with any type of master cylinder including the stock one.Of course the leverage ratios may be wrong , the master may not pump enough fluid for proper braking and a built in drum brake residual valve may drag the discs excessively.The Mustang cylinder is used a lot because its inexpensive, compact and the piston size is reasonably close.
