I have a 2005 silverado with a 4.8. I put a v3 cheater cam springs,push rods dual timing chain,headers and true dual Exhaust in along with heads that stole compression from my engine because I listened to someone who didn't know what they were talking about. Now I want to change my heads from the milled .05 317s that I ignorantly put in, to something with smaller combustion chambers. Have not done a compression test but I know its low. I have even thought about putting stock heads back on that are ported. Any ideas? What is a safe size chamber to go down to. I think 62cc is what is stock.

 

Both SDPC and WCCH have a ported 5.3 head that will work well for you. You can even have them milled if you want a little more compression.