I've still got the original front calipers, never rebuilt, on the front of my
69 164 at about 290,000 miles. I used to have dragging problems because the
hoses were swollen shut. The little rubber boots are in bad shape and I
occasionally get some rust on the pistons (maybe every 4 or 5 years). I used
WD40 in the old days and Blaster more recently, pressed them out against worn
pads and pried them back in 5 or 6 times until they eased up and they are
still fine. I'll know I have gone too far when they begin to leak but they
have not so far....

Have you verified that your hoses are not swollen shut? Brakes work OK but
don't let all the way "go".
--
George Downs Bartlesville, Heart of the USA!