Partial VIN's were stamped at the assembly plant, Norwood began stamping the partial above the oil filter on the side of the block in December to avoid removing the alternator. From discussion on the the CRG, VN cars were intermittent; a lot if not most of them were stamped on the deck until later in the year. The stamping shown in the ad looks plausible in comparison to my only 350 example (my Z11 block stamping is pictured), but the ad doesn't show the partial VIN. I would guess that it would be on the deck if it was legitimate -
Regards,
Steve