This is why I have said over and over, "There is no such things as an OOTB cylinder head from the factory." Every head has to go to a trusted machinist and be checked and fixed.
And people want to know how come we charge more for an engine than the crate motor facilities. I will not install an OOTB cylinder head on any engine we build.
Nothing gets installed OOTB, every piece is inspected. You would be suprised how almost everything needs some correction, piston rings, rocker arms, valve springs. We get cylinder heads in here from one source where most of the valves would cut up the bronze guides when we pull them (if we didn't dress the ends with a fine file) and they have never been run. Never run, and some of the valve stems are so nicked up during the spring installation we have to replace those valves. Most of the time they will run screwed up, some of them for a long time.