The component with the lowest price in the GASKET KIT A schematic is the Washer,oil Bolt.
On this parts fiche the Seal,valve Stem is the most specified component.
Parts such as the Gasket Kit A: O-ring,21.5x2, Gasket,cylinder H (nas), Seal,valve Stem, Washer,oil Bolt are included in the Vf750c Magna 1983 (d) Usa Gasket Kit A parts fiche.