Any Shimano (or shimano compatible Microshift) 6-9 speed RD with enough capacity for your gearing will work. Google derailleur capacity.
FWIW the RD pulleys are replaceable.
For rear shifters any Shimano (or Microshift) 7 speed flat bar either mountain or road will index. Front depends on what derailleur is on there as typically you need either a mountain shifter for Mt. series FD or road shifter for road series FD. It will also need to be triple chainring compatible.

All new index compatible housing and cable is going to be a good idea as well. New brake pads for the old dried hard ones is recommended.

Most bike chains today come with a quick link master link. Normally new chains are too long and need to be shortened to size with a chain breaker. Any 6/7/8 speed chain is correct. Google "chain sizing" for a couple different methods of sizing.

https://www.parktool.com/en-us/blog/repair-help

https://www.youtube.com/channel/UCaA...2xiBbAUVZsvDYQ