I think that I'm answering my own question here, but I suppose if in the ME you chose AGL, then there is no way to know beforehand what MSL is at that point, unless you have both working radar and barometric altimeters adjusted for atmospheric conditions (or GPS I suppose).
Edit: Actually, I searched my install folder for Batumi, and found the airport diagram, or Aerodrome Chart, and it shows 33 ft./10 m. as the elevation at both ends of the runway. So, 1533 MSL should be fine.