You do not need to put any sealant in the grooves, just make sure the grooves and the sealing surfaces on the heads are clean. If there is any residue from previous sealant, make sure to clean that all out well.
You DO need to put some sealant on the heads near the camshaft caps per the FSM. About 1/2" long on the flat parts and about 1/2" up the arches of the camshaft bearing caps. That's 16 places for both heads.
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