There are some late 73's with this valve cover. As the plant ran out of GT specific parts they used Manta parts much like the change to the rear tail lights on the 73. I have had 2 GT engines with this valve cover, both were 73's, I recently sold one of these valve covers to a lady in Florida that wanted to keep hers OE.It sure started nicely. I wonder if the head has been replaced, the valve cover for the GT is different. I’ve seen worse but there’s more than a few tiny rust spots. All in all it looks like a manageable restoration project. See if the reserve gets exceeded, if so by how much?