Try Dave Shadel at Performance Specialties in Gardner, Nev.
As I recall hearing, he was the only guy on this planet that has any parts for those engines.
Here's his contact info:

Performance Specialties
P.O. Box 3146
Gardnerville, NV 89410
Office Phone: 775-265-7523
E-mail: [email protected]

Say Hello! to Dave for me. We are old friends.