Tonearm suggestions

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.

The Audiomods is a modified Rega RB250, albeit with new bearings etc. The arms are quite different structurally.
I have actually heard both arms on a Rega P9, the RB1000 was more precise sounding, and to my golden ears cleaner and more articulate, provided the VTA was dialed in on both arms.
Agree with the Helius Omega, an interesting arm, and SME IV, they are both good options and to my ears superior to the Rega/Audiomods.