At a minimum you need to replace the compressor, dryer and orifice. Given it's just a leak you should flush the system but it's not 100% necessary. You will need to have the system completely evacuated and not just a quicky job. I'd let is sit on vacuum for a good hour given the system has been open so long. And then of course it has to be charged.
As mentioned earlier the dryer is a ***** because the threads seize. Be really careful on and off, but changing it isn't an option. The system is full of moisture and the descendant bag has absorbed all it can.
The orifice can be changed by pulling the right turn light and working gently on the line. Go all cave man and you'll induce a leak at the condenser. No need to replace the condenser unless you had a catastrophic mechanical compressor failure and you can't get it to flush clean.
Pay attention and work clean. buy the right o-rings, not just what autozone has in stock or what's easy to get. Coat all the o-rings with A/C oil and be careful not to cut the rings on install. There are lots of little things the DIY guys can mess up, but if you pay attention and use common sense you'll be fine. Don't leave the oil open when not in use. It's hydroscopic
and will be ruined in a few hours.
Reman compressors suck ***. I will not install them on my own stuff. They are failures waiting to happen. I know we'll get stories about how someones reman lasted forever yadda yadda yadda, but that is not the norm. I personally only buy factory quality compressors. Delco or Denso would be my suggestion. I'm sure you would rather do this once and not every year, don't cheap out because of a few stories where the guys got lucky.
ASE master tech for over 30 years.