That bass would be worth a lot more if it was restored to original condition, but you would need a talented person to fill in the space routed out for the original pickup re-location and do a refinish. I don't know if there were any factory Black bodies from that period so you would have to check that also. Possibly some original neck color in the neck pocket or neck pickup route. Maybe the original pickup route by the neck is mostly undisturbed. I don't know what the extra knobs or switches are on the pickguard but those would have to go also.
There should be a date stamped in both the neck pocket and on the neck. Not necessarily the same date but should be reasonably close.
You should disclose any restoration efforts to a potential buyer. The cost to restore might be equal or greater to the going price for these basses.
As it sits, I wouldn't offer more than $300-$350 for it provided you love the way it plays and sounds. If you find anything you don't like I would pass.
Rick B.