all the plating companies sell/supply pistons these days that I'm aware of.
once you send them your cylinder, they'll be able to tell you how much they'll need to bore it out...if any at all.
If for some reason the damage is beyond what they can supply a piston for, they'll let you know...but be sure to let them know you want them to contact you if there's any problems.
Most plating companies have the ability to repair some pretty damaged cylinders these days.
Some even have a "cylinder exchange" deal...where you send them your damaged cylinder, and they'll send you a refurbished one for an "X" amount of dollars.
Not sure where you're located...but if you're near the east coast, then PowerSeal is a very good choice...if you're near the west coast, then Millenium Tech is a very good choice for platers.
http://www.powersealusa.com/http://mt-llc.com/