Billy Goat
WKR
Shot in the dark, but I've had an old brake hose give the impression the caliper was bad. Sometimes the inside of the hose deteriorates and as it does it can act as a check valve trapping pressure in the caliper.
Replacing the brake hose is relatively easy and inexpensive thing to try.
-Dan
That's not uncommon on old vehicles. I have seen it on a few old farm trucks.
But the rotor rubbing the caliber indicates that it's something more than just a caliper not releasing.
Went from what should be friction to interference.