that overheating hubub is from the chevrolet camp. mostly anything over .030 over on those chev smallblocks you'll have problems. the 400 is EPIC for that. nevermind just the steam ports in the head. but yah generally .060 on a 360 is no problem.
Oh yes,I remember distinctly a ride in my buddies mid 80's malibu that had a mild 400.He made a full throttle pass up Scott road hill in Surrey.Anyone who knows this hill knows it's quite steep,maybe better than a 10% grade. Anyways,there was steam jetting out of the breather after we pulled over. He cracked the heads...
The chev smallblock is a very light,thin casting.
Funny thing is I could hammer on that 318 all day long and never a problem.
Funny thing is the car was a dog.My 318 74 Duster beat the pants off it all day long with just a 4bbl,cam and duals.Still had ex manifolds too..I always seemed to have at least 2 car lengths on him,lol!
Ashton go to Mancini and have a look at the mopar performance engines that are discounted.Theres lots to look at.