I have a pair of 10128374 LT1 heads that are lightly ported to clean them up. Right now the valves and springs are not installed so they have to be installed. $250 plus shipping. I can email pictures if anyone is interested.
Jeff

 

How much of an increase would these provide?

 

I have no idea. They came with the 68 Camaro I bought and I need the money so I'm not putting them on the car. You would probably want to do some more porting to them to see a significant flow increase.

 

Am I just seeing things or is that a hairline crack in the 3rd photo?
Or is it a scratch?

 

No crack, it's a drag mark from the grinding tool. The picture makes it look worse than it is for some reason.