Jazz bass pickups come in long and short versions cause Fender used different length pickups for the neck and bridge positions. There are a TON of replacement options. What sort of sound are you going for? Does the hum that comes from a single coil pickup bother you? Active pickups like many of the EMG models require a battery and replacing the pots as well (though the EMG stuff is pretty easy to install), do you have room for a battery? Are you capable of making room? Or would you want to pay to have a battery box put in? If you don't want the battery then you need to be looking at passive options (which again, there are a ton of them).
Good point about the rout. I put a pair of Fender 62s on a MIM JB and they had to do a slight rout on the bridge pickup rout to get it to fit.