Rob, since my bike is still in a thousand bits, I have no idea how many washers go there, but if you call my good friend Robin Markey from Bob's Indians in Etters PA, I'm sure he can tell you off the top of his head, and they sell parts too.
http://www.bobsindian.com/
Tell him I sent you! (ask for Robin in any case)
He has what must be the most photographed 640 in the world, if you google Indian 640, you will see all kinds of sdtuff with his bike on it!!
Below it is, some years ago, for a change he's on the back, and I'm riding it.
Cheers,
Lex