You have seen this done before, or do you know this specific bike?
I know the bike. The owner is very active on the "other" Thunderbird forum. I don't know if we can link to other forums here, so I'll just say that it has 1600 and Thunderbird in the name. You can Google it from that. For what it's worth the owner seems like a pretty straight forward guy, and he took good care of the bike. So if you do buy it from him you will be getting a well maintained bike as far as I know.