Upgrading Technics 1200 Tonearm under $1000

My analogue setup:
  • AT9 cartridge
  • Herron vtph-2a stage
  • Bryston 4b3 amp
  • Bryston Model T Sig speakers
  • Moon Neo 350P pre
  • Technics 1200mkII

I upgraded the Technics with the obligatory fluid dampening technology - a must for anyone listening at higher volumes. Wires are upgraded to the cardas all purchased from KAB! I also stripped the tired silver paint and painted the plinth a pearl white. The tonearm is the only piece left to update! I'm struggling with the amount of choices out there that is easy to set up. I looked at the Rega RB330 as a possible candidate but I'm open to other suggestions.
can also try a belt drive or idler with suitable tonearm. Or... change to a good MM like what Chakster suggest. 

both option will make the system much  more musical warm textured and liquid.

making it sound more detailed and accurate can sometimes work against. seeing your using bryston. 

audio technica with ceramic inserts or headshell is also very good. smoother and more musical. that is another  cheap and easy upgrade option.

easiest tonearm upgrade would be SL1200MK4 titanium arm

This is very rare old model from the 90s for domestic Japanese market, the price is insane and tonearm is not easy to find separately. The OP already rewired his tonearm, so the only difference between mk2 and mk4 is the armrube (aluminum vs. titanium).

I remember the price for new Jelco tonearm on ebay was just about $450-550 in 2019, I think it’s a good alternative to the stock arm even if the price was increased. This is a perfect match for Technics and better than Rega tonearm.
IMO you will have to spend more than $1000 to significantly upgrade that arm. I do see some people replacing the arm on the 1200G model.  Maybe they would give you a deal on the old arm?

1200G turntable cost $3500 and prople who replace the arm looking for $5000 tonearms normally. The stock magnesium tonearm is great on 1200G.

But OP’s mk2 turntable cost $400 (in Japan they cost $150 used today) and he willing to buy a new tonearm under $1000
The Rega tonearm is not an upgrade. You would probably be better served to upgrade your cartridge or buy a turntable constructed to more easily accommodate different tonearms.