Need help identifying valve covers

[RobertC5]

Can anyone help me identify the proper origin for these small block valve covers? My father used to race stock cars in the late 1960's, and it was not uncommon to have used a Corvette motor, although I guess he could have used a SBC from another vehicle as well. I THOUGHT these were correct for 58-62 Corvette. Any input would be appreciated.

[carboman]

They look like the ones used on Corvettes from about 62-66 on base engines

[Tony B.96LT4]

I believe the early vettes used the offset holes for the hold down screws. These look like the later ones to me.

[Rick and Arleen Ball]

I think these are 67 Base 327/300HP.
These covers were also used on early 283s. Chevelles, Novas, and Impalas.