Rear Caliper piston rust

[Kneale Brownson]

I noticed while replacing the pads on the rear brakes of my wife's 4kq
camping car that the rubber boot on the caliper piston was torn, so today I
took the caliper off to install new rubber bits.  I found that the piston
had a ring of rust right on the chromed edge next to where the rubber boot
fits.  That was easy enough to remove, but there were a couple spots on the
chrome where there were rust spots maybe as much as a quarter inch down the
chromed surface.  I tried smoothing them out with one of those flat files
they used to use to file ignition points.  That took the sharp edges down,
but there's some rust pitting I couldn't get to.

Will these rough spots  tear up the rubber seal in the caliper cylinder
ID?????  Should I be looking for some new calipers?