Yes, it can be bored and sleeved to standard to reuse your pistons. But, that would probably cost a lot more than just boring and new pistons. Sleeving requires boring, honing to sleeve o/d, pressing in the sleeve, and then honing the sleeve to size. A lot more labor than just boring and honing.
If your rust isn't too deep, a glazebuster type hone with lots of oil ( I use diesel ) to keep the junk washed off might clean it up. Try one and the measure the amount removed.
