1982 Ford E-Series Van Master Cylinder

Yes, the master cylinder needs to be bled too & that should be done 1st. There are some kits you can buy @ auto parts stores but you can do it with just some flexible tubing. Remove the lines from the master cylinder & attach short lines that re-direct fluid right back into the master cylinder (top off) - you're just re-cycling the fluid. Have someone pump the pedal & when you get no more air bubbles as the fluid comes out of the master cyclinder, thru the lines & squirts back in, then you're done. Re-install the brake lines & bleed the brakes again.

The correct answer would be to ditch that old master cylinder and get a new one. Forget what the original owner did. Raybestos is good. Wagner is over machined.
Don't take a chance with your bones or another drivers'.
If the lines are original, it would be wise to replace them with armoured brake lines.
Never skimp on brakes.
Cast iron master cylinders tend not to melt as easily as those weird plastic ones.