I don’t know about cc’s as yet but the head is 4.000” thick +- .005 and parallel when untouched and I find a granite table/height gauge quickest for detecting thickness/parallelism. The casting thickness from deck to jacket is 3/8”so removing .090” puts it at 3.91”which is probably safe or if you can live with ¼” to the jacket then 3.875” is about minimum (1/8” total removed). If it cleans up parallel at that value or maybe a little less it should be usable but plan on some combustion chamber reshaping which becomes polluted as radiuses are replaced by sharp corners affecting exhaust flow. Custom pushrods may be a cost effective solution too.
