There are no replacement seals available to re-seal the calipers if you take them apart. There is fact may not be any in there, just super precision machined surfaces. Leave them alone.
You also will ruin the caliper if you hone the bore. This is not a master cylinder with a honed surface, it is precision polished and chrome plated.
So is the piston. If you damage the smooth, shiny surface of either, they won't slide, and will stick. Unless damaged, they last indefinitely -- the ones on my 220D are mostly original, and the car is almost 30 years old. I did have to replace one -- corroded piston from running rotors under minimum thickness and consequent sticking with severe overheating.
The seal retracts the piston enough that the runout in the rotor will push it back. Old seals get hard, and then the brakes drag.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!