These valve covers are a genuine GM Restoration Part. They include the 'casting flaw' — a line that runs through the O in Corvette (visible in the image below). In addition to this flaw, these valve covers have a LOT of other flaws, and the aluminium is very uneven in colour and texture. Out of the box they look awful, be prepared to do a lot of hand finishing if you want them to look any good on the car.
These covers are not correct for this car. The exact date when the casting flaw appeared is disputed (some say mid-'65, others say '66), but it was not present in early '65. The Red Rocket's original valve covers did not have the flaw (one of the original covers is still on the car, the other is with the car but cracked).