Need help!

Needing some help here. I had a master cylinder go bad after 21 years. It started leaking out the rear of it. I could fill the reservoir and had great brakes but after it sat for a few weeks, it would be low again. I replaced this master cylinder with another remanufactured unit, which actually looked like a brand new one. With this one, my front brakes done very little braking. The rear drums would try and lock every time. Took this one back and got a brand new master cylinder, cardone 13-1571. This one does the same thing. Everything bleeds out good. All air removed. Front rotors have a slight drag on them and rear drums are free spinning, but when test driving the fronts don't help at all and the rears try to skid. Check the rod length, it has free play. Linelock will not hold whatsoever because front rotors won't grab tight enough. When up on jack stands and spinning the wheels, them seem to grab because I can't turn them by hand. It is in a 1974 duster with power disc/drum brakes. Don't want to put manual proportioning valve on it because of originallity. Shouldn't have to because of everything is original and worked fine before. Any ideas? Please help. Thanks guys.