With an old car, your best bet is to stay away from dealerships completely as they don't know the old cars at all. If taking the car somewhere with techs that don't know the cars, it would at least be wise to take it somewhere cheaper.
As The_Twin mentioned, the best bet are BMW specific shops that still see cars this age on a day-to-day basis if you're not going to do the work yourself. The E30 is much, much easier to work on than newer cars like the E46 because everything is accessible without loads of covers and electronics are simple (+12V, ground, and whatever item) as opposed to the modern, digital signalling.
BTW, safety should be limited to things that affect stopping and controlling the car. None of the engine systems should affect it. They don't care if the car goes, only if it can stop and turn (and a few other things like headlights, wipers, horn, etc.)