Tonearm suggestions

I'm unfamiliar with your turntable, so take my advice with a grain. If you're interested in Rega arms, take a look at Origin Live arms like the Illustrious 3C or, at a higher price point, the Conqueror 3C. The "C" versions have carbon fiber wands, which are suppose to be an improvement but the older ones are good, too. OL arms have the same geometry and mount as Rega arms but they're generally considered to be better.

You could also look for a used Graham 2.2, which you can pick up for around $1,600 give or take. I owned one for years. It's not perfect but it's very good, and one of the best deals on the used tonearm market, IMO.

Good luck.

I'd take a look at the Audiomods options and the Funk FXR.

Bot have been reviewed by Jason Kennedy.

The RB1000 is much better built than the Audiomods, but is more difficult to do VTA as it requires spacers under the arm base. For your deck I think the RB1000 will give better performance. I've heard both arms and would consider the RB1000 to be more precise.
Why not get an Audio Origami PU7 which seems to be what most Palmer buyers in the UK are using. I'ts Rega mount, and I think you could get a new one for US$2500 ex UK or talk to Hammertone the importer. RR $2900 - surely they can do one for $2500.

All the Origin Live tonearms use the Rega mount. So does the JA Michell and other modded RB250/300/301/303 arms.

I am using a Rega 1000 on my LP12. Works very well; I bought the Moth OEM version as it is $1200 rather than $2000; only lacks the Rega logo. According to UK reviews they are identical otherwise. I am using Pete Wriggle's VTA adjustor which will add another $200 or so to the arm cost. I was using a Graham 2.2 previously and it is a good arm also but I am going with the RB 1000.