Calipers occasionally seizing (both)

More than likely there are rings of dirt on the pistons and the calipers need to be rebuilt. When you push the pistons back in to make room for the new thicker pads, that dirt gets pushed under the square-cut seal, then they can't slide in and out freely. We used to rebuild calipers and wheel cylinders with every brake job as late as the early '90s, but today professionally-rebuilt calipers with warranties are really inexpensive, so buying them is the better value. Few instructors even teach caliper rebuilding any more. If you want to attempt it, I can walk you through the procedure.

Auto parts stores will have the rebuilding kits or they can order them. All it contains is a new square-cut seal and the rubber dust boot. You'll need to clean the pistons with brake parts cleaner. If you find any of the chrome plating has lifted, including it formed rust spots, do not clean those off. The piston must be replaced as it will not seal when those defects work their way out to the seal as they self-adjust over time.

As the brakes are seized can you loosen the mounting bolts for the master cylinder to see if the brakes release? If so the push rod from the booster needs to be adjusted inward about a 1/8 of an inch. Please let me know.