Brake question and advise please

[engineer_gregh]

Sorry for the lengthly description but looking for advise. When I stored the truck (71 C-10 front disk and rear drums with power brakes) a year ago the brakes worked, but once stopped the pedal would creep down until it bottomed out. I assumed the master cylinder was bad. Now its time to get it back on the road; the left rear wheel was locking up when applying the brakes when I backed the truck out and took it for a run around the block. Replaced the master cylinder, both rear wheel cylinders, rear shoes, spring kits on the rear, two hard lines at rear axle, two hard lines from porportioning valve to master cylinder, and two hard lines from porportioning valve to distribution block and juction at left front lower control arm. Bleed the master cylinder and all four corners. Good clear fluid at all four corners, emergency brake works great, and truck stops evenly. Problem is pedal goes almost all the way to the floor and brake light is on. Sorry for the lengthly description but looking for advise.