On this parts fiche the O-ring,15x2.5 is the most specified component.
Parts such as the Gasket Kit B: O-ring,15x2.5, Packing,dynamo Co (nas), Gasket,clutch Cov (nas), Gasket,oil Pump (nas) are included in the Cb750c 750 Custom 1982 (c) Usa Gasket Kit B parts fiche.
The Honda GASKET KIT B has eighteen products enlisted in the schematic.