Assuming that the basis is a legal casting accepted for the stock engine (pre-59 automotive, pre-56 for bikes), is there specific language that describes permitted and/or prohibited mods using only the original head plus fabricated (not adapted later) parts?
Some tough calls that could be cited as a precedent?
Do the block/crankcase and head have to be part of the same original engine if both are XO?
What kind of parts are you taking about? Valves, guides, roller rockers, etc. are acceptable.
Parts don't have to be from the same original engine, but do need to be from the same make/model engine. I think if you try and adapt a Ford head to a Chevy block, it may move you to XXO, as it may be comsidered a 'specialty head'.
I would pose a specific question to Mike Stewart.
