You would need to call the shop and speak with someone there. You may want to have some ideas in mind. For instance, a top mounted cavity plate in a contrasting wood might be an idea; like the plate on
this bass. Or they may even be able to find a wood that's similar to the very nice top wood that your bass already has. As for the electronics, at the very least you could have them replace the selector switch with a pan, unless you prefer the selector. And you could also have them add bass and treble boost/cut switches. Upgrading to a second filter and Q switch would probably be a bit more involved. The seller mentioned some screws with rust, so you may want to have them replace those as well.
This is a very nice bass with that top and the Purpleheart lams. With an inlay on the top, a refinish may be needed; but that should address what the seller described as bumps, dimples and dents. Also, I would recommend getting a satin-feel finish on the neck. Oh, and aluminum side dots while you're there.
All of this may be more than what you had in mind. I'm just kinda throwing out ideas. When I sent my Essence to the shop, I tried to think of everything I might want to have done to it since it was going to be there anyway; then when I called, we had a good starting point for deciding what we wanted to do.