Last time I did my brakes I was lazy and cheap and I only changed my pads. Now my rotors are finished (all groved and a lot thinner) and they're noisy as hell...still brakes but the pedal isn't as high as I'd like and the noise can get annoying.
Don't be cheap like me, change pads and rotors, they're not that expensive on E30s. Remember to clean and grease the guide pins, clean the pads carrier and inspect the caliper boots for tears. Also clean the hub and put some anti-seize before puting the new rotors. Inspect the hand brake linings and adjust them if necessary.
Like KenCopperwheat said, a flush would not be a bad idea since I suspect your liquid is quite old. Bleed the brakes after.
Btw, make sure you pump the pedal a couple times before your test drive. I think that's all...