Well in Australia where I am located these seem to be rarer and i can only find two that have been sold online and they both went for around $1000, so i guess around $700 in America atm. The higher holes for the tub bar is original but did not come with the barlower two arent original, but its cool to see one with the bridge cover and knobs intact!
That sounds completely reasonable to me. These bases are very uncommon. I wouldn't be surprised if the right buyer came along and you got even more than that.
DO NOT mess with the electronics. That will destroy the resale value. In fact, don't do anything to the bass.Do you have any recommendations?? Im not to familiar with single coils of that size!
Even with the repositioned (replaced?) string guide on the headstock and the extra holes in the guard, it's still nearly stock. Cleaning it up and oil the fingerboard (lemon oil or a specific fingerboard conditioner will be fine) but asside from changing the strings anything you change about the bass will only hurt the resale value.
Best of luck whatever you decide.