When replaced my ac compressor this summer and installed everything I did the following:

Bought a complete AC o-ring set (you'll want to replace every single o-ring in the system)

Bought a small bottle of PAG lubricant for the compressor and o-rings (I went with sanden check what lube your compressor will take)

new receiver dryer

new high pressure switch

new fan switch on receiver dryer

new expansion valve (very easy to replace on a w123)

I also completely flushed the evaporator in the car with just generic ac flush sold at the autoparts store as well as the condenser on the radiator.

Replaced the electric fan (my old one did not work when jumped directly to 12v)

I would inspect your hoses. If they don't have any cracks when you bend them I wouldn't get them all replaced / remade. I used my original hoses and switched to r134 and everything has been working well all summer so i don't think I have any leaks.

Side Note!
Be sure your cooling system is in good health. Every single part is new in the cooling system of my 82 240D with the exception of the radiator that seems to be in excellent shape and it still will heat up in drive at idle for an extended period of time (say 15 mins). My engine runs right above 80C when the ac is off but with it on depending on traffic and stopping (at a drive thru say) it will creep up to 100C and sometimes a touch higher which makes me anxious enough to turn off the ac for a few mins so it cools back down.