1989 318 coolant issue

Radiator should be full to top, reservoir bottle should be between MIN and MAX marks- if overfilled, it will push coolant out of the overflow onto the ground after shutoff. You do have the factory reservoir and not a smaller aftermarket one, right? The reservoir bottle does NOT get filled to the top- it needs the extra volume to contain the coolant during heat cycles.
Is the engine actually overheating, or is it cooling normally?