Does a 1965 GTO have matching numbers stamped on the engibe block?
Does a 1965 GTO have the VIN # stamped on the engine bloc and if so where can it be found?
Guide to Pontiac V8 engine identification. https://www.hagerty.com/media/maintenance-and- tech/identify-pontiac-engine-blocks/
According to Hagerty the VIN is located on the passenger’s side front of the block, down where the timing cover and the oil pan meet. I suggest you contact PHS for information. There is also a book about authenticating GTO's.
They had a 2 letter code like YS or WT. Below that was a 6 number engine unit number like: 356289. Nothing to link back to the VIN