There are enough details available in the photo to pin this bike down as having a 1936-1937 Cleveland Welding built Double-Bar Roadster frame. Changes made to that frame during late 1937 show the bike to be pre 1938. The serial number could pin down the date a bit more closely.
From what I can see there is nothing else on the bike that is likely original to that frame. The fork looks to be CWC but the light strut marks that as 1940+. The other parts (with the possible exception of the #3 Wald stem and the bars) are a mix of parts from other bikes and generally newer than the date of the frame. That said, it has developed a very unifying patina and nothing on the bike is way out of period or character for a prewar model.