I wouldn't expect the manufacturer to design and produce the very best, optimum, chamber right out of the bucket. It's a constant improvement in design. I wonder what the 60's closed chamber heads looked like? Probably not the optimum design. (regardless of car company) There isn't too many optimum choices of Mopar small block heads with closed chambers. We're talking 318 here and not big bore 340/360 big valve/ big port heads. 920's are good, #302's are good and so are Magnums. #302's have hardened seats as do the Magnums but they take a list of parts to make them work. Just sayin'.