What you have there is a mix of parts!
That frame is a 1945-1948. I know this because of the location of the kickstand mount, which is behind the engine plate on the left side. There looks to be several modifications to the frame, such as that hook welded to the right side and I'm not sure what those things welded to the clutch anchor points are for.
Your bike may be a pre kick start model, as kickstart wasn't added until 1947. They did make a retro fit kit for some earlier models.
The engine case is a later model, probably around 1956 vintage, but has an early, pre 1949 cylinder on it.