In 1952, Balboa Hospital (the Navy Hospital) was located at 32.72529,-117.148021
Put the coordinates in Google Maps. The Navy outgrew the facility and rebuilt to the immediate east. The old Navy Hospital became a park property a few years ago in Balboa Park.
410 Elm is the Occidental Hotel (32.724393,-117.160628). It may have been used for overflow, but it is doubtful. It was more likely someone's home address. Many other park buildings along El Prado (east of 6th and Laurel) were used as overflow facilities during WWII for example. During the Korean War, there may have been similar needs.