Disc brakes locked

I am completing a ground up resto of a 70 duster340. Front disc rear drum with manual master cylinder . I have bleed the master cylinder twice on the car with no air present. I have billed the entire system with noir present on the second bleed. I still have a soft brake pedal but more importantly both front discs are looked solid. Opening bleeder release wheel lock. Do I have a bad master cylinder or other. I am also suspicious of the secondary step down / delay valve that goes to the rear brakes. Could that cause the wheel lock also?

Thanks jeff