DFV Piston Information

[FJBH10]

Hey all,
I have recently come across a sale online of a DFV piston claimed by the seller to be used by James Hunt in the '76 Japanese GP, from the photos I can see it has a part number that I could ask for. Does anyone know how or where I might be able to find out whether this is true? I am interested in purchasing it but am understandably a bit sceptical about his claim.

FJBH10

P.S Apologies if this is the wrong forum section