@solypsa the P2S on the 2.2 is 218mm, 9" effective length (pivot to stylus).
A constraint is that the arm assembly can protrude from the underside of the armboard a max of 1 1/4" before it hits the suspended plinth or sub-chasis. The dia of the hole in the armboard is 1 7/8".
I believe I'm going to need to have a disc/plate made that sits over the large diameter hole in the armboard. If I can find an arm that's secured only by a locking nut and doesn't require smaller drilled holes offset from the main hole, then I'm good as long is it doesn't exceed 3.25" from the top side of the disc/plate. And the outside diameter of the locking nut mustn't exceed 1 7/8".
As @lewm @jwei @wrm57 have suggested, a Phantom might be a good choice. But I'm not sure that I can take for granted the idea that it will be a drop-in replacement for the 2.2
My next step is to find a detailed drawing for the Phantom!