I remember that bike. If I could have figured out how to swing it........I purchased and re-sold a GL-1200 with just under 1,000 miles about two years ago.
It was authentic, and a forum member purchased it from me - as a "museum piece".
In this case, I'd really want to see the bike in person to determine if I really thought it was authentic or not. Could be.
But not worth 8,000 in any case.