Good news on the 65 C-10 brakes. We replaced the defective Vette master cylinder with a reman one from the auto parts. This one is for a 71-early 80's chevy pickup. The primary chamber is the rear one and is larger than the front. I switched the lines around to fit it and put it on after bench bleeding. We had a good pedal before we even bled the brakes! Now they are exactly as they should be.
I think I learned some lessons here. I don't think a Corvette cylinder is the best idea for disc/drum because there is no primary chamber due to the 4 wheel discs.
Anyway Deb got to drive her truck again and now I can get to one of my projects. I just wish she'd finish the bodywork on the tailgate.

'65 C-10, 65 L-60, 65 C-80, 72 C-60 & and a bunch of old Chevy cars.
Never time to do it right, always time to do it over.