From engine No. 20-1 120 615 (05/1955)
Piston pin for 1300cc, 1500cc and 1600cc aircooled engines.
Diameter is 22mm and the length is 72mm
Piston pins used in the 25 and 30 (USA 36)HP engines.
Diameter is 20mm.
This is the cover plate used on the 25&30PK crankcases.
The online Porsche PET 356 pre A will guide you towards Porsche part number 616 106 083 00 which was renumbered from 539 06 524.
As you can see below this part will not fit the two piece crankcase.