[markjohnson]

"Dont forget all of the Z16 engines had the last letter of the code hand stamped X
This looks like a 65 built engine if I'm reading the casting !"

This is exactly how my Z-16 engine was, with the 'X' hand stamped. I bought that engine at a bank parking lot swap meet in St. Louis as a 4-Bolt main .060 over 427. I ran the engine for about six months, spraying Nitrous through it and everything before I took the time to actually decode it and discover it as being a real Z-16 engine! Apparently, the 1965 4-Bolt castings had thick enough cylinder walls where you could bore them out to 427's......and then some. Sorry for the OT