Ross used the name Custom deluxe for years, and that chain guard looks very similar to their styles. All the old Ross Custom Deluxes I've seen have a different style frame and chain ring, although the patina on yours matches up. The frame sure looks like Murray though. The rims match so they may be original. Maybe the guard isn't the original though. A closeup of the dropouts may shed some light on the manufacturer, they all have unique dropout designs. The original color will show if you take the forks off, on the inside tube the paint is usually like new. And on the frame, if you pull the cranks, there may be some of the original color on the inside of the BB shell. That will verify that the forks are the original also.
But nevertheless, it's a 50's bike that looks to be in good shape. A nice find!