As mentioned, those pickups are already passive, it's your pre-amp that activates them.
You could run a passive volume and tone control for each pickup and make use of all 4 knobs you currently have. If you did want to replace the PUs, there are plenty of mfgs that make a PJ combo. Almost every one of them will be passive...there are very few "active pickups" available. It's the onboard pre-amp that makes the bass active.