Rivet Source for 1960 Grumann 17' Sail Canoe

Hi everyone,
Hope you and yours are doing well. I’m posting this for a friend who is not terribly Internet savvy. He’s trying to refinish a1960 Grumann 17’ Sail Canoe. I’m looking for a source for the two-part T-6 Alumite (aluminum) rivets. It’s a two-part rivet… can’t be hollow otherwise it could take on water. So both parts have to be solid.

Not really sure what else to include… does anybody have any sources on where to find these rivets?

Many thanks for your time in reading this post.

I would go right to the source in Marathon NY. Grumman/Marathon Canoes.