There are several shops in Cali that can help you out. Take a peek at the sponsor section on the homepage.
It is best to have your machinist inspect the cylinders first before ordering pistons to determine how much the cylinder needs to be bored or honed in order to clean up any damage. Then and only when they have pistons in hand can they properly size the bores to the new pistons.
Also, if it is an old stock motor, it's probably time to just do a total tear down. At least put new seals in the cases, new outer bearings on the crank and have it trued and welded.