Quench

Dare Devil, the head didn't get any closer to the piston, but more so the valve when opening.

Brambles, it's the combo you have and in a heavy truck. Thats why it pings. Where and how is the distributor set up?

Whats a small Comp Cam?

On the head, unless you went overboard of the exhaust port, you'll be OK. It's not as much of a problem as you may thik since the exhaust port is the biggest resticktion and is the port that needs the most improvment to reasch a better balance in the heads.