Nick, if your compression numbers are good, paint it gray and enjoy it. I have a 1964 261. The only way it can be 1964 is if its a replacement block. No numbers on the distributor deck at all! They did some strange things back then. Nobody will ever know your engine isnt original to the truck. If those compression numbers come back poorly, get a 1955-1962 235 or better, a 261 to replace it. A little modification, but nothing earth shattering. Good luck!
