I originally bought the adaptors and valve covers in 1986 from Butler Racing. I used them on my car for about 2000 miles. I'd be happy to send you photos of the components showing the condition and I'll sell them if you are interested.
Arthur
It looks like the link I posted above may not have worked, so I have posted another link below to my Cobra build album on Facebook, I hope this one works. Scroll through the photos and you'll be able to see the engine bay with the Ford valve covers on the 350 SBC.
https://www.facebook.com/media/set/?...1&l=0d9c5c8c6d