In the meantime -- Mike Rich, of Mike Rich Motorsports near Scranton, Pennsylvania, specialises in Moto Guzzi bikes and might be able to help you with finding parts. He has helped with Tom Liberatore's Goose -- which has set records at the Salt as recently as last summer. For that matter -- you might contact Tom (no, I don't have information and he's not a regular on this Forum) and ask if he can help your search.
And back to the specific question -- you're best off if you ask and get a response from Tom Evans, chair of the Motorcycle Technical committee, or Van Butler, head motorcycle inspector. I think they're both identified (and contact information given) in the rulebook.