Ah, my specialty! I've had 4 of these and they are great basses for upgrades.
Both pickups are 3.7" wide, so you have to find them that size. Also, the 19mm spacing is a concern as well. So yeah, Fender size is a no-go. And from what I've installed, the WORST CASE SCENARIO is you have to file down the corner of the pickup that goes into the bass and they'll just drop right in with no damage to anything.
I used SADOWSKY HC pickups to great effect. They make the bass sound SO good. (There's a used set in the classifieds right now.) Very clear and defined tonality and will bring out the best in it.
The single coil version works nicely as well, as a direct fit. Either are available from Sadowsky direct.
DIMARZIO ULTRAJAZZ 5 will also work. They actually make (made?) the Sadowsky pickups and are slightly cheaper. But they sound incredibly similar.
If you want to go active only, EMG makes the LJ pickup size.
NORDSTRAND makes the NJ5 and NJ5S.
DELANO makes a number of pickups that fit the size. They are pricey, but damn good pickups
Beyond that, there's a world of custom makers that would do whatever size you want... but the cost and wait time make it a little silly, IMO.
Check out bestbassgear.com, they carry a lot of stuff!
Any questions, feel free to PM me, I've had a lot of fun with this bass over the years.