Give the cylinders a good cleanup with a dingleberry hone, and then measure taper wear before you get concerned about rust pits. If there's over about .005" of taper, you'll need to do a rebore job and use oversize pistons. That will clean up all but the most severe pitting. A 69 block will handle a 60 over piston with no problems- - - - -I've run those blocks in 500+ HP round track applications at well over 7K RPM.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!