I agree with mrpearson re: having a look at Realparts.
I have used the Gotoh 103B-T on several builds and they're great. Much better than the ABR-style kit ones. Realparts doesn't have it in black, but do in chrome, nickel and gold. FWIW they're good value.

That brass bridge is not designed for G-style nut slot. It's for a ST or TL type. Personally I wouldn't use it on those either, but that's just me. I would go with bone or Tusq or similar.

I'll also echo mr. p's sentiment about how you spend your money within your budget. You will get more improvement out of upgrading the pickups than just upgrading the pots. If you have a set budget, swapping the pickups and nothing else, is going to give you the best result. Better quality pots won't make unremarkable pickups sound remarkable, and lesser quality pots won't make remarkable pickups sound unremarkable.

I know it goes against what most people do here, but you may want to consider not over-capitalising on your first build. (said the kettle to the pot ). You can always upgrade bits & pieces once you have it finished and playing nicely.