While I've never used this specific valve cover, every factory Ford cover I've ever seen had the lip around the sealing base to help hold gaskets in place.
The original sand cast ‘67 Shelby GT 500 valve covers, with the “Cobra LeMans” all in a line do not have a lip on the base for the gaskets, they are flat. That doesn’t help dozz302 with their question, and I don’t know enough about original ‘68 Shelby valve covers to weigh in, but don’t use the lack of a lip alone to determine if a set of aluminum valve covers are original or not.
I agree, I have a pair of aluminum pentroof "Cobra 427" valves covers, that my cousin gave me in 1973. He bought them in 1966, when he was racing a new 66 Fairlane. These covers were gray, not black, and weigh about twice as much as the typical repro "Cobra LeMans" covers I have seen. The spark plug holders and steel baffles were riveted on, not screwed, and have flat gasket flanges. And unlike the factory aluminum 428 CJ valve covers I have, the Cobra 427s have a rougher, (sand cast? )texture on the inside.