new pickups for Warwick Fortress

Hi guys. I've got a Warwick Fortess One, and I've been seriously considering getting new pickups (P/J). I'm looking for a fat, warm sound, and from what I've been reading, it seem that Bartolinis are the best choice. The other thing, is that my bass has active electronics and active pickups, so I'm not sure whether It would work to put in passive pickups. (I would prefer passive). If anyone has any pickup suggestions, or anything else that may be of importance, I would greatly appreciate it. Thanks. (This is my first thread).