Yes, that part is incorrect. Should be a copper gasket.. Yours looks like a seal from a ball bearing or something.
There's recently been some talk about this gasket, and where to find it. Copper gaskets like this are standard industry items, and when I have a chance, I'm going to check the McMaster-Carr catalog.
I'm sure there are a number of Japanese bikes that use a part, which will work fine. Need to figure out which models those are.