No, he wouldn't (be disappointed I mean)! Because that is a picture not of a lame SG-Z, but of George's former one-off SG Bass built in the late nineties (not by the Custom Shop though) with a fat Les Paul Standard neck, a fatter body than the SG-Zs (or the SG Standards/RIs of today) and not Z-pups, but (chrome or even nickel) TB Plus pups. It sounds as forceful as a Les Paul Standard with lots of oooomph. I should know because I talked George into selling it to me! The only drawback to this bass is that it has nothing of the lightness, sleekness and playability of a sixties EB-0 or -3, it's a chunker of an instrument, even more massive than the maple neck seventies EB-0L or -3L. More RD than SG!
To bring some light into this matter, I have asked my Gibson contact about this mysterious SG long scale.