First the obvious - could you be resting your foot on the brake pedal, new car, small foot well and all that?
If not, has 1965 had a recent brake MC replacement?
Sometimes such a change over winds up with a piston rod being too long - the rod leaving the booster and pushing in the MC piston. When things warm up, things get a bit too long and your brakes are now in the 'on' position without you moving the pedal... voila - heat and locked brakes.
Easy basic check is wait for a cool car and pull the MC free of the booster-don't pull it all the way off or undo any lines, just unbolt it and pull it away. If pushing it back to the booster mounting flange requires a compression of any sort, things are probably too long.
Some rods are adjustable, others will need cutting/filing to a shorter length.
Check this out first.
Next is dirty, sticky calipers and that fix is more of a pain.
Larry
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