What are these marking?

the 63 is designed to use the plug tube ends as the gasket so you need to remove the factory spark plug washers. IIRC only the pre 63 and the later peanut plug (no tubes) heads needed the factory washer.
"..The '63-up heads have a redesigned counterbore at the top of the spark plug hole; the spark plug tube itself seals the plug, and if you use the washer it interferes with heat transfer from the plug to the head. The '60-'62 heads don't have the special counterbore and need to use the plug gaskets. This is factory info..."
SS Dan.

<< Dont know what that graffiti is on that motor but I would be a little pissed if I saw that on the showroom floor model! >>>