"It use to freak me out every time I had my 451 apart, heads looked terribly corroded on the intake and the exhaust sides, and they were cnc ported/polished. It looked like chunks of aluminum were sand blasted off. Motor ran 9's for many years though and plugs always looked good. "

Prosport, mine are only corroded on the exhaust but also some in the combustion chamber also. Pretty much everywhere the gas is being burnt.
This is a race car only and I do use Nitrous a few time a year but only up to 250 HP shot and it is a conservative tune up with plenty of timing retard.
It does have a sand blasted look to it!

My plugs always look good.
Mike