[tbirdtbird]

"The head was resurfaced twice before two gasket changes; it had a slight twist both times."

Clearly a problem there.

If the owner keeps doing the same thing he should expect to keep getting the same results. Something is wrong. I'd have the deck re-checked maybe even by a different machinist. A simple straight edge does not get you where you wanna go

If he is not gonna give up on the 9# cap then I would love to know what the operating temp is on this baby. If he is running much over 200 then this is way over design temp and in fact that may be contributing to some warping somewhere. These are not freshly casted blocks; they are 85 yrs old and fatigued by many many temp swings