Thoren are pretty easy to fix up. You can get a TD160 super or any of those belt drives, they are easy and fun. Easy to add whatever you like as far as tonearms.
Most of the parts interchange. The 121 and 124 are a lot nicer but they are for recording, broadcasting or transcription. Playback really doesn’t need the speed to be perfect. Recording from it, could be an issue..
They have a GREAT factory suspension and a LOT of easy inexpensive mods too. As I mentioned a lot of the parts interchange on the light belt belt drives. I keep a cool 1/2 dozen on hand. TD124 and Russco are my favorites. You can always use a pedestal mount or mod the plinth for a pocket drop & swap.
Regards