What pickup should I put in my old Carvin

Hello, fellow TB'ers. I'm looking for suggestions...

I bought this old Carvin LB40 a few months ago for $400.00 and I love it. It's not my primary bass (I have a couple of Precisions--one with flats and one with pressurewounds--that I play with the tone rolled completely off), but it is a blast to play. The neck is a little bit narrower than a P or J, the bass has wonderful sustain and is naturally bright and focused due to the hard rock maple neck and body, so I use it as my "round wound sound" bass for recording when I want a little "zing." But I've been kicking around the idea of replacing the pickup. From what I gather, the existing original pickup is essentially a guitar pickup. I'd like to increase the output and add some warmth and depth and punch. So... What would you recommend? I'm thinking maybe a Guild Bi-Sonic, or does anyone make a "guitar humbucker" sized bass pickup with similar qualities that I could drop in without having to rout the body, or ...?

 

Ooh, that DiMarzio looks really interesting.