The Jaguar HB appears to have a format similar to EMG-35 style pickups. A lot of aftermarket pickup makers make pickups in those enclosures or are willing to make them by request. TB's David (SGD Luthierie) commonly makes pickups of that format, and he makes several variants of them, so you'll have quite a set to choose from.
C.Linton, if I may, "killing" one coil of a humbucker is a coil split. A coil tap would mean you "kill" a portion of the windings of a single coil so less windings remain in circuit to capture the sound - it would give a cleaner, if less loud, tone, but it's rarely done on basses.
As far as the electronics go, it's a bass with passive pickups and an (active, obviously) preamp: if you ever wish to change the preamp you can go for a different three-band one, or you can go with a two-band and plug up one of the knob holes somehow, or you can even go fully passive and put a passive volume and tone control in there. The possibilities are basically endless. You have to figure out the tone you want, and the electronics can be done onwards.