Over the past year I've got various bits and pieces to do this, some might say its crazy to do this instead of just buying a better bass but where's the fun in that and I probably wouldn't do this with a better instrument. I think I've finished it although I'll probably redo the wiring at some point.
https://drive.google.com/file/d/1W-qGmTuJjaD-2TgUlEltjEhvuttRZBU7/view?usp=drivesdk
Wilkinson (cheap) p pickup, sounds pretty good and almost noiseless, less noisy then the active EMGs I tried before.
Dimarzio (2nd hand) ultra jazz, again, sounds decent and virtually noiseless
Pickups go into active balance, then into active bass/treble/variable mid stacked knobs, then volume and out. Volume is push/pull and switches to passive mode with just the P pickup going straight to volume and out.
Bit of overkill for that bass? Probably, but its been fun doing it and I'm quite pleased with how it's ended up.