Not Main and Sunset but seems unlikely two restaurants so close to each other would have the same name (unless 'Soochow' is a generic name for a certain kind of cuisine or simply the bowdlerized version of 'Suzhou').
Soochow Cafe, N. Los Angeles Street, Herman Schultheis, 1937
Two smartly dressed women pass the Soochow Cafe located at 504 N. Los Angeles Street in Old Chinatown. This is the only Soochow Restaurant I know and it's wedged next to Jerry's Joynt on Los Angeles Street.
LAPL
street scene old chinatown, los angeles (calif), circa 1940
Los Angeles Street at Ferguson Alley. Jerry's Joynt, the Soochow Restaurant, Lugo House, Terminal Annex and the tower at Union Station.
UCLA special collections/Los Angeles Times