In the late seventies, early eighties, Buchholz certainly dabbled with Gibson basses, though you mostly see him with a P. I saw him play a whole concert with a natural Grabber (or maybe Ripper, I was unable to differentiate between the two back then) on the Virgin Killer tour in 1977 (thought the bass horribly fugly then) and he played a Bicentennial on a Jap TV show plus did the Rock you like a Hurricane vid with a NonRev. And of course Rudolf Schenker and Mathias Jabs were good Gibson Custom Shop customers with their Flying Vs and Explorers they solely (Schenker) or mostly (Jabs) played.
Last I heard Buchholz was in the car parts/brakes/friction systems business doing very well (his home town Hannover is a hub for that type of industry), it seems that following his less than glorious and non-voluntary departure from the Scorps for tax fraud, he built himself an industrial career. He must have played a few gigs with Uli Roth lately (he and Uli were in Hendrix-type three piece "Dawn Road" which merged into the Scorpions after Michael Schenker had left for UFO) and I heard from a record company guy that he was even in the studio with Uli Roth, but nothing has been released so far.
Uwe