All personal opinion I guess. I love my power steering and if you can't find a decent set (calculate that most sets will require on overhaul with freash seals and all) there are a few here that converted to electrical power steering, for example through
www.ezpowersteering.com they have a custom kit for the E21.
AC on these cars, I wouldn't expect too much. These sets will also require a full rebuild and conversion to more modern gases, but what you'll end up with is a kit that only blows cold air from the center vents. Easy for me to say as I drive a Baur, but I wouldn't bother.