I had a similar situation with my 67 Z. The original owner went through the engine sometime in the late 70s and it had never been fired. I was tempted to prime the oil pump and start it but cooler heads prevailed and I had a friend go through it. Good thing I did because I found the original main and rod bearings were re-used. Another issue was the rings were stuck in the ring lands due to old assembly lube drying out. There were some other issues as well so it was money well spent going through it.
BTW, me and my buddy thought the valve springs would be shot from sitting partially compressed all those years but each of them tested good!
https://www.yenko.net/forum/showthread.php?t=176109