Might try to contact John Clegg. They have fielded lots of quick Pontiac drag cars. They probably know the best place in south TX for Pontiac machine work.
http://missiongarage.com/photos.htm
I don't know anything about this place. But they list a "Pontiac 400 GTO Ram Air lll V8", with cast rods. The price is low. But, it probably has the 8-eyebrow cast pistons. But, they advertise that they build custom engines. "Each of our engines can be custom built to your specifications." Might be worth checkin out.
http://www.rebuiltcrateengines.com/p...v8-p-2155.html
http://www.rebuiltcrateengines.com/custom_quote.php
"...are the rods and crank balanced with pistons as a rotating assembled unit.."
Yes. The entire rotating assembly is all balanced together.