If the M.C. is above the highest point on the brakes like a stock Mopar has then the residual valve maintains pressures on the pads not letting them retract all the way, no need for the valve on disc. in my opinion
I installed a SSBC front disc kit on my 1955 Dodge Coronet and used a later model Mopar brand aluminum dual piston M.C. for a later car that had disc brake application that I assumed that the residual valve was not there, it was and when I would push the car out of the shop into the sun the change in brake fluid temp. would make the car harder to push back, untightening the front brake line cured that when it burped fluid out of the fitting
I'm building a 1940 Ford Tudor sedan with 4 wheel disc with the M.C. mounted under the floors and I used the Wilwood 3 lbs. residual valves in both lines to avoid allowing the fluid to drain back into the M.C. over filling it and making me have to pump the brakes to stop