I just bought a set of 862 58cc ported/polished heads for my 04 GTO. Will I have valve clearance issues? What pushrod length and head gasket would be required?
Cam is a 581 lift.

 

you might be ok with the stock cam but i would do the clay method just to make sure clearence is good . those are from a 5.3 truck engine if memory serves .
are you running the stock cam ?
you can get some better info if you post up in the internal section . just trying to help and good luck on your build bro .

 

Its actually a comp cam 581lift. I just bought the car used and have the ported 5.3 heads and a fast 90/90 setup ready for it as well.

 

If cam duration is at or below 228 you have a better chance of clearing the pistons,-but still check ptv-better safe than sorry.With 58 cc heads my preference would be the factory mls gaskets at .055 ths. to help keep the compression more pump gas friendly.This is just my opinion.They have links on this board to help you with static and dynamic figures on a givin combo.

 

The duration of the cam at .50 is 225/227. The lift is actually 571/571

 

i would check it just to be safe since you got a cam . the valves in the truck heads sit lower than ours . off the top of my head a 241 iss 66.5cc and for it to drop 58cc that would be like 8.5cc . so .007 shaved off for every cc would be 8.5x.007 would be close to .059 milled off a stock 241 or 853 like on a fbody .