The HU Community process helped yet again.
When I posted this thread and sent out an email to the Belem community, we heard from Alex Reis, a member of a local Belem motorcycle club, who got in touch immediately and offered help and friendship to SgtMarty. He also knew a mechanic, Silvio, who has worked on Kawasakis; unfortunately, the sprockets that Marty needed were not available locally so he had to wait while I shipped them to him. Alex and others helped make sure that Marty enjoyed his stay.
Long story short, the parts got there on Monday the 16th; the bike got reassembled on Tuesday, and on Wednesday Marty and the KLR departed on a boat headed up the Amazon to Manaus. So all is well and the saga continues.