Brake pedal sticks
I'm gonna just take a wild stab and guess more towards......
A nearly 50 year old car sitting and rusting
Could be rust corrosion in the master cylinder / booster
Rust / corrosion in the brake pivot bearing.
Could be "a lot of things" related to that extended period of time.
What happens when you work the pedal by hand? Does it feel "stiff" coming back up?