I had an '80 320i.
I recommend replacing all of the rubber hoses. Specifically all of the vacuum lines - these cars run terrible with the slightest vacuum leaks. Don't forget the main intake boot and the injector seals. You can do 100% of the vacuum lines, boot, & seals for about $100 and it will be like putting in a brand new engine.
You should also consider a rear sway bar which stiffens up the handling quite a bit - you can pick these up at a wrecking yard for about $15.
Mine: RIP
