Mike , if the heads are off and off to rebuild there is a option. Up grade the valves and harden seats installed. Then lead free is a moot point.
I was lucky the care taker before me did that.
I worry about the stock valves any way with the multi groves on the stem. Driven on the street and never over rev, they may be good.
How is your engine on octane requirements? Mid grade or premium to avoid knock?
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