brake bleeding firm now spongie.

The above statement makes me wonder.

Tighten the 'ELL out of the rear shoes, get 'em TIGHT so the wheels won't turn until you get them bled.

When you bleed (and maybe you are) have your buddy pump up pedal with ALL BLEEDERS closed. Open one bleeder only, and close it when fluid starts to slow down (pedal to floor) CLOSE the bleeder BEFORE you allow your partner to release the pedal back up.

Then pump the pedal AGAIN if necessary to get a pedal.

There should be a retainer that prevents the master piston from returning too far. To repeat, I'm wondering if it's returning far enough.

You should be able to pump up a pedal, hold it, and remove the filler cap on the master, and release the pedal. You should see movement of fluid back out the ports in the master floor. Older all drum ones typically actually "fountain" up above the fluid.