Ooh, it comes with a set of keys. An innovation like that has gotta be worth an extra $1000.
"Prospective bidders must satisfy themselves as to the mileage covered." How the fuck are they supposed to do that? Track down previous owners and strap them to a polygraph machine? That statement is something of a red flag to me. It actually raises suspicion that the indicated mileage is a crock of shit.
The bike itself looks good to me. I can't pick any inconsistencies from original, but I don't know much about 750 twins. I wouldn't expect an old bike to be 100% original anyway, even though the seller implies it is.