It looks like a refinned Studio (disco'd several years ago) to me. The headstock looks correct for that model as does the flat non stepped body and set neck. Gibson has done a lot of very interesting one off things over the years, I've never seen another like this but I'm not too surpised looking at it. It looks like it has a S/N stamped on the back of the headstock, care to share it?
Endorsing Artist Mike Lull T Bass pickups