Curious boat indeed.
What is that horizontal ridge on the transom?? Looks almost like a welded seam on a riveted boat!?
Very geometric/angular splashwell cut out. Definitely seems pretty unique.
If it's a pre 72 and assigned a HIN it could be anywhere (or nowhere) due to it often being the owners obligation to place it correctly.. I found one that wasn't in any of the normal locations behind the motor's control box. Couldn't see it at all without unbolting.