Brake Question

[zooming993]

I’m working on my 70 El Camino with factory disc brakes up front and drums in the rear. I’m in the process of replacing the master cylinder along with the booster. The prior owner installed an adjustable proportioning valve, which I will be replacing with a CPP (PV4) proportioning valve. I bought the PV4 because I’m also installing a CPP rear disc brake conversion kit. My question has to do with the factory distribution valve mounted to the frame. Does the PV4 valve replace the distribution valve or do I need them both?