Spyders didn't use a gasket. They used a phenolic board, like an old orange-ish-brown circuit board.
I couldn't find one with a blank space big enough. But I found a modern epoxy circuit board, around a 1/16th of an inch thick. It's a translucent green. Anyway, I cut it slightly larger than the crest and sanded a bevel on it all around. A dot of silicone top and bottom keeps it from rotating. I drilled the single hole and used a push-nut on the underside of the hood.
Biggest Spyder faux-pax ever? Using a 911 crest, they're WAY too big.
Extra points if you can find an early 356 crest that has orange instead of red in it.
In the early 2000s, Dario Calandra used to sell all manner of Spyder parts that looked correct. The crest underliner was one of them. He also sold e-brake handles, shifters, mirrors, plexi windshields. You could go broke getting it "right".