SSBC front disk brake converion on 67 cuda, no pressure, HELP

Is you pedal rod adjusted properly? It shoud seat on the master cylinder and keep the pedal all the was up ( with a slight amount of slack). The valve Sanguine was talking about would be a proportioning valve ( it gives the correct proportioning for the front disc/ rear drum setup) It would also require a residual valve ( that keep 2psi on the rear brakes at all times fro the drums to work properly). They can both be had in what is called a combination valve.
For you not to be getting any pressure at all I would start looking at the master. I'm not saying it's bad, but if your brake pedal isn't giving it the proper travel then it would be like pushing on the pedal slower and not as far. Kind of like compareing 1.6 ratio rocker arms to a 1.5.... the travel isn't the same so you get differant results.