Check out the Probe #14477 it is cut for, and includes spirolox retainers & it has a 1/16 ring pack, and i'm pretty sure it it is machined from a TRW/SPEED-PRO forging blank. Try FLATLANDER RACINGS web site. Hope this helps.
9SECVSIX, if interested in Probe forged pistons, check out ebay item 280269135817. Looks like you can purchase pistons, pins, spiral locks and rings for $401.99.