I've heard EMG Hz pickups passive and they are not terrible that way. I think if you were to wire the pickups like a Fender J-Bass (vol - vol - tone but using 500K pots as the EMGs are humbuckers) like so:
and take the pre-amp out of the circuit you should be good.
Are the pickup cavities and control cavity shielded?
In terms of other pickups to plunk in there and wire up passively, I'm a fan of the Bartolini M45s (EMG-40 replacements for 5-string). You can usually find pairs of them floating around here used on TalkBass.