That's a very cool find, and I believe this is probably the TB-2000 that John Kahn owned. BUT, I'm skeptical of the seller's claims that Kahn played it a lot, and that the modifications were done while it was still in his posession.
A couple of years ago I scoured the Jerry Site for every single pic I could find that showed John and his gear in the pre-steinberger era. There were exactly two shows where I found pics of him playing this Bean:
7/9/77, TB headstock is clearly visible. http://www.thejerrysite.com/shows/show/1325
11/26/77, these are by far the best shots of him with the Bean and it appears to be in stock form. The neck pickup is definitely stock instead of the chrome mudbucker in the auction, and I think you'd see the DiMarzio P-bass pickup if it were there. http://www.thejerrysite.com/shows/show/1284
The two surrounding shows with decent pics both show him with a Precision.
the very next night he's back on a Fender, looks possibly like a brand new one as it appears extra shiny and the colors are consistent with a common 1977 model.
So while the evidence is fairly thin, I find it hard to believe that he played it enough to cause that level of wear, and I also find it hard to believe that he made these mods. ALL of John's basses that I know of were stock except two: The '58 Sunburst P that he swapped in a Leo Quan Badass II bridge and DiMarzio pickup, and an Olympic White P that got the exact same treatment. (I found exactly two pictures of this white P, one in 1980 and another in 1981. I suspect it was his touring backup as surrounding shows featured the '58) It doesn't seem likely to me that out of all the Fenders he went through, the only bass he really seriously tinkered with was this Bean that he only played twice that we know of.