As noted elsewhere, my RD had a tragedy some decades past and is now on the way back to normality, sound wise, + a refin ...
The Moog is long dead and buried but the undamaged pup runs fine on a 500k pot in the bridge position, passive, and the damaged one in the same position on my Peter Cook "Tequilabird" Custom, same wiring...
Thanks to George I now have a slice of 70's Mud to fit in the neck position on the T'bird (albeit I will need to do some minor mods to the internals as there is no way to rout the space required, but not tragically, just a strip and resolder, plus line the cavity to screen the lower end of the coils), also, thanks to Tony (Tubehead), I also have a 20/20 pup (which did not suit, soundwise, but fits the neck slot of the RD, as was noted when sent) which I intend to remove the original coil and fit an EMG select, same type that I have on my Hohner Jack... I like the sound of these pups and I have it, so QED... this will mean I do not have to mess with mounting an odd sized pup in the RD's big pup slot...
I prefer not to run with much in the way, and mostly no tone control, but as I now 2 basses to rewire I would appreciate some suggestions...
I'd go with 3 volume controls with 500K pots.
If you want, you can put push-pull 500K pots wired like killswitches for the pups, so you can turn off whatever pup you want by pulling out its volume pot.
edit: there's a schematic. On the left is the simple (just vol controls) on the right the more complicated with the three push-pulls.