Match this 500hp/500lb-ft Combo?

You need to have a purpose when porting. You don't just go all out and then throw it on the bench see what you got... that's a sure way too lose power and kill otherwise perfectly good heads. When you're familiar with the head ...it doesnt take much on the exh side.. especially if theres a decent valve job that meet the chamber wall, bowls around. All the aluminum stuff is easy to get the exh working...even over working. You move in small steps with the exhaust.
What's always struck me... is how high a ratio the chevrolames run... they'll have 260 int and 220 on the exh... is the chamber that bad..lol