542 grams Ross Forged 292 Piston
From an old ad Tom had, I just did Bing on "292 piston"
http://www.ebay.com/itm/292-Chevy-Forged-pistons-040-/280830089780Probably lighter than stock but maybe close as they use stock rods.
Guessing that's about a 600 Holley and headers on your car, did you ever figure out the cam specs?
Cool pic anyway.
I would think even a stock 292 is good to 5000, is this not true?