Used pair of original Valve Covers off Chevy  283 Engine. These have the "Chevrolet" script on each valve cover. 

They have some surface rust, red paint that was not done at the factory, and some expected wear.  One of them has a small ding at the very end at the top.

The holes are 8 7/8 inches, on center, apart from each other.

These are far from show quality but can be blasted and painted to look great again.

NOTE: These DO NOT have any Breather or Oil Fill holes; this style Valve Cover was used on engines that had the oil fill tube through the intake manifold.

I am nowhere near an expert on these items however, I will answer your questions to the best of my ability.