Refreshing a long neglected 77 XS top end and an age-old question comes to mind: what sealers (if any) to use on both the base and head gaskets? They are new Athenas. Gut tells me to go ahead with a thin smear of Permatex aircraft for the base, and nothing (except maybe around the chain tunnel) on the head gasket. I have heard though that the newer Athena base gaskets are chemically treated and require nothing but clean surfaces to seal. Any preferences out there? TIA!