What kind of Headers are these? (Just added pics)

I know this is quite the shot in the dark, but the guy building my engine ask what kind of headers I have for gaskets, I bought them used so I have no idea. The only name/number I have found says "510"
Is there a 510 header?? I just says 510L or 510R, I assume for left and right.

Maybe I should just look into new ones? These are in pretty good shape, just surface rust.

To be sure, do these even look like a 73+ A-body header??
Thanks!

Header1.JPG

Header2.JPG

hedaer3.JPG