I agree with Yarddog except that it's a lot of work to bring back oxidized aluminum... It really isn't, especially if you do it a bit at a time and know the drill.
So how much are you willing to spend? What sort of riding do you want to do on this airhead? Do you like working on your bikes?
Everyone has his favorite, and for different or similar reasons, but they're all wonderful bikes - 1970 all the way to 1995. It's just important to narrow down what qualities and characteristics are important to you.
Then we could recommend which machines would be a match.
Wanted: Dead, smashed, crashed or trashed gauges
BMW GAUGE REPAIRS - TACH*SPEEDO*CLOCK*VOLT METER *PODs & LIGHT BOARD*