How far I can go with tonearms on my Thorens 124?


I have recently bought and upgraded Thorens 124 tt with silicon motors grommets, new belt, oiling (if that counts for upgrade :), waiting for silicon mushrooms for the base and silicon nitride ball and new gasket and housing. I was very pleased with all small upgrades (rumbling level is one to mention). I have SME 3009 II impr (early one with Shure logo), and ZYX R50 Bloom which I love tremendously, no doubt why Audiogon is full of ZYX discussion, it is sad it did not go for FUJI straight ahead :).

I have a feeling that I could get more from the tt with replacing tonearm (which I think a basic arm by all means). I am biased because TD 124 is 50 y.o. turntable which has its limitations of the age, yet certain charisma to love in it, so advanced tonearm, which I could use later on another TT might not benefit on current one...

Tonearm choices (I am sorry if touching already happened discussions, hence it might tt related), I lined as Schoeder Model TWO, Morch UP-4, Tri-planar, Graham and Hadcock (GH228).

1) What would reasonable level of the arm to buy, yet to use later on other tt (say Orbe)?
2) I am likely to search used ones, which of those would be easiest/most difficult to get (I am not in hurry, but some might take years for search)?

Of all what I read, Schroeder sounds like the best choice, I am just confused with lead time and how that works...

Thanks in advance.
salavat
Looks like the search is down to Moerch and Shroeder (if I am lucky to find used one). Is there a significant difference b/w UP-4 and DP-6, actually questions is would be there such a difference on my TD 124?

Thanks to whom already responded.
I would recomend Jachim Bung's "Swiss precision - The story of the Thorens 124 turntable" to anyone who owns one of these classics.

FYI - the book was reviewed in stereophile some while back.
I actualy use the TD 124 with Graham Phantom / Jan Allaerts Finish as my reference . It is a combo made in heaven. I suggest some upgrades for the TD 124 to perform the best : 1/ Slate plinth 2/ Slate tonearmboard 3/ remove the rubber mushrooms and tight contact with plinth 4/ Strip motor clean and lubricate ( cf analog dpt.) 5/ strip bearing clean and lubricate 6/ Idler wheel noise reduction kit (Schopper) 7/ new streched belt 8/ good power cable.
Graham Phantom is a top performer and no need 12" tonearm in this application, so you conserve the original armboard config.
You can mail me for more info. Best.
Jean.