Everybody's got me worried about my Vortec's now
. The heads were off of a warrantied motor from a local dealer. I think they had 10,000 miles on them (piston crapped out). They are the 906 version. All that was done was a valve job and new seals. The seals were from the 69-80 Fel-Pro Gasket kit. The rocker arms are stock. The cam is a comp 4x4 extreme with 210/218 .447"/.462" lift. Does anyone know for sure what stock heads will tolerate. So far I've heard .400", .420", .460", .475", and .480" Quite a little room between estimates. I worry too much, lol.