Personally I wouldn't go too hogwild over the electronics for that bass...not to denigrate it at all, but it looks like a basic, no-frills kind of bass that gets the job done without being fancy, so I'd save my extra money for great pickups for the warmoth build. I tend to like hum-cancelling pickups, so maybe a Bill Lawrence P-46 and J-45 set? His are very reasonable in price compared to other small winder outfits.
Your playing style (pick, fingers, slap, combination), string preference (flats, round, etc), desired tones, musical style, etc. all have a huge amount of influence on pickup selection. But in this case I would honestly lean towards just selecting a less expensive though tried and true set. While Dimarzios aren't usually my first choice I remember playing on a kid's starter bass that the previous owner had stuck a Model P and Model J set into, and it was a pretty cool bass for the money. I would just get a good working P-J set, and my preference would be a humcancelling J.
If money was a concern I would consider actually giving the GFS ones a run for their money. Next in line would probably be a Bill Lawrence set. High end stuff like Fralins, Rio Grande, Nordstrand, et cetera, just seem like they'd probably be wasted on what is likely a good solid bass, but probably not a vintage relic designed to absolutely nail that classic 1962 tone or whatnot.
If you want an extremely simple but effective bass....replace the neck P-bass pickup, and just unwire the bridge pickup and leave it there as a dummy pickup. You save money, less controls to fiddle with, and the list of classic bass riffs recorded with just a P-bass pickup is near endless. Anyway, just another idea. If you want that nasal J-bridge sound, you'll want the J pickup still a part of the circuit.
