There is a lot to unpack there.
You could have a whole forum dedicated to Technics mods and carts.
I would google search KAB mods and Carts that match well the that arm and decide what works within your budget.
I am about to fire up my old 1200 mk11 table and perform a few KAB mods. I'm thinking the fluid dampener, tone arm insert, and a rewire for starters. For Carts considering a Nagaoka, a little warmer presentation would do well with my system.