My Chilton service manual lists the camshaft-to-thrust plate clearance at .001" to .005". This is set as the timing gear is pressed onto the cam, with the thrust plate in place. Since the entire assembly is contained under the timing cover, I see no need for a gasket, unless there's something there that's not obvious. It might be that the gasket is used for establishing the end play, but with a pressed-on gear, I don't see how that could happen. I've used a feeler gauge blade between the thrust plate and the cam gear while pressing the assembly together to establish the correct clearance.
Jerry