I think it's too bad they did'nt pump out some more info from the previous owner since he/she also was the original and only owner. My guess is it has been modified after purchase simply because the control plate material looks considerably thicker (the white layer) than what Gibson usually used for their two ply. Maybe the original very thin and fragile plate was a victim of the usual output jack accident, and when making a new control plate, the owner opted for a sturdier material, got rid of the optional functions not used, while adding what the owner thought was missing (maybe individual vol controls?). Furthermore to prevent any new accident they put the input jack on the side.
Also I wonder what's with the label tape on the case. "1979 GIBSON LES PAUL "TRIUMPH". THE INSULT RECORDING BASS"