Hallways and stairways waste space so really try to minimize them. 

To convert back would take costly new permits and removing an external stairway and door.

I never actually saw the original applicant again after lease and keys....the actual tenant was a stone cold gangster pimp(not to be confused with the suave type pimp) and had his girl turning tricks in the apartment, he had numerous confrontations with tricks that resulted in fights in the common areas and one time a big hole smashed in the wall of one of the stairway landings that was from him throwing a guy down the stairs.

I just have to add a doorway at the top of the stairway which I had intended on anyways. 

Be patient and look at our failures as just another lesson on your stairway to financial freedom.