There's a 606 S. Coronado on the 1906 Sanborn Map, with the corner lot to the north empty. A building permit dated January 11, 1910,
provides for moving 606 S. Coronado to 283 S. Coronado, where it appears to remain today.
The building at 600 S. Coronado also occupied the former site of 606 and stood from 1910-59. Below at upper left is 600 S. Coronado
on the 1950 Sanborn, on the SE corner of 6th Street:
ProQuest via LA Public Library
Here's a fuzzy 1925 aerial with 600 S. Coronado at upper left:
EXM-P-S-LOS-ANG-CIT-BUI-095 @
USC Digital Library
These next two photos are undated but I'd guess c. 1940. Here, 600 S. Coronado is below the dog and cat food ad:
DW-SD-93-23-112 @
USC Digital Library
This is the closest view of 600 S. Coronado I could find:
DW-SD-93-23-112 @
USC Digital Library