Parts such as the Cylinder - Chart: Plug,spark (w20fp, Cylinder Head, Gskt.cyln.head (nas), Plug,spark (bpr4h are included in the Sb50p E 1990 (l) Usa Cylinder - Chart parts fiche.
The seventeen Sb50p E 1990 (l) Usa Cylinder - Chart component parts are all listed in this schematic.
The lowest price component in this Cylinder - Chart parts-list fiche is the Stud, 6x27.