I'm learning on this also & from what I gather(so far)you want to have the correct length pushrods(for milling/thick/thin gaskets or a factory stack of heck height tolerances) then check the wipe pattern & adj w shims(or deepening the rocker stand saddles in rare cases and guys have used soft copper washers as shims(just check/bevel the ones(s)on the oiling pedestal so they dont impede flow & have had zero problems.