I know it's a big ask but could you send me a wiringIf that's a Dimarzio Model P, then I'd definitely recommend doing something like:
- Remove everything in there
- Wire the pickup to a 2-way DPDT switch for series parallel
- Make a P bass wiring harness
- Install the switch between the knobs
- Install the volume pots on the outer 2 pot holes (jack stays where it is).
The Dimarzio P sounds great in both modes, meaty and full in series, crisp and clear in parallel. It would eliminate the need to plug the hole and actually makes it useful.
If it weren't that pickup, you could still possibly do similar wiring, but if you didn't even want to mess with parallel on that, you could just do a "mute" switch there and it would be fine, too.
Or... just add a plug to the hole!
Those are what I'd do, personally.
Old school Matsumoku basses are great, so it's definitely worth making it a functional beast.
diagram for this set up please.
) of the opportunity and go that route. V-S/P Switch-T would make for a killer, very versatile bass. Quite a looker too! 
