If the brakes worked before the work you did, then you either have a defective mast. cyl. Or there is air still in the system that is all it can be!!! Are you bleeding from each bleeder screw and not trying to bleed from the line connection due to stuck bleeder screw?
All you did was replace the parts you said right? Pads, calipers, shoes & wheel cyls. are all good right?
Now clamp off the rubber flex lines, pedal better now? Bet so. Then BLEED THE BRAKES! May take 1/2 gal. or more of fluid.