I think it's really cool to attempt ANY full-on salvage job like that.
...but it might be quite a chore -- both for searching out parts AND paying for them -- if you're going for a restoration, rather than just making a playable bass with available parts. If you want to take a GREAT (IMO!) body/neck combo & custom-build your ideal axe, that's tres cool
Central to a resto would be the active EQ circuitry. I've seen two XB versions, one with all four pots mounted to a big circuit board. Finding this component could take a year or three AND cost you a few hundred USD.
Or you could buy an aftermarket kit or something salvaged , or just leave it off & make it passive.
Then, you'd need to locate suitable pickups. For the better XBs, every one I've seen has had "four-tab" pickups, J-type or double-J. Looks like your project has been carved out from a J-size -- which is fine, as you can likely now drop in something from EMG or Bartolini or whatever.
An EMG 45DC active set gives you two soapbar pickups, & four pots with all the electronics mounted & ready to plug together (solderless), so it's fast AND reliable AND there's about zero chance of messing anything up.
But there's that COST thing: if you dig around, you can probably find a new 45DC set for under $300.
And you're kinda buying blind. FWIW, my Warmoth has pretty much that identical EMG set (dual concentric knobs & all) &, truth to tell, I don't like the tone quite as much as what I get from my four-knob XBs.
Meanwhile, here's an XB-600 -- with all the hardware -- for $250 + s/h.http://www.guitarcenter.com/Washburn-Used-Washburn-XB600-Natural-Electric-Bass-Guitar-110687336-i4043050.gc