Took the intake off an original 1970 318 engine. (40 years ago.) The end seals were not leaking. I took it apart to look at the cam/lifters.
The end seals were a soft material, that was fairly stiff but, I could cut it easily. I'm guessing it was neoprene closed cell foam.
Is that what you are asking?
I doubt you can get that style gasket anymore. Could buy some neoprene strips and make your own.
