80’s 318 compression ratio figuring out where I’m at.

OK, that typically would be .050-.060" of milling to get that chamber size with the larger open chamber heads. Maybe your machinist can comment on going further, and others here who have done so. It seems like there have been a few cases of going that far reported here.

Maybe the pushrods have already been shortened. IIRC, the adjusters would have to be turned about 2.25 turns to accommodate a total of .090" head change (if the cam's base circle was the same as stock); that might get some of them pretty far backed out. A thin shim (just 1 thin shim) under the rocker shafts on each stand would help that a bit.