Here's a link, which you may have already seen, to the pick-ups used in the Geddy:
http://www.fender.com/products//sear...tno=0992123000
They are going to sound the closest to the original Jazz bass sound. I think if you experimented by changing the settings on your amp to more of a funk setting, you would find the sound you're looking for. Generally, for my jazz basses, when I play in a funk-jazz setting, I set my EQ to have more emphasis on mids than the general "smily-face" setting most often used for music like that, that way I have a good solid tone for slap, and a growly tone for fingered funk lines.
But, if you do decide to change the pickups, I would recommend taking a look at the Dimarzio J pickups, they're cheaper than the CS 60's, but still have a great sound.