That's definitely a Murray built bike. Could have been badged as Murray, Mercury, J.C. Higgins or a number of other brands. The "bathroom floor drain" style chainring as you say is a dead giveaway and the skip tooth type puts it pre-1950 or so. I love the gentle curve of the frame's downtube, more elegant than Schwinn or Columbia IMHO.
Here are a couple of examples of similar bikes. The black one is mine and originally had the cranks like your originals but were bent. I just happened to have a ladies Schwinn lying around in excellent condition and robbed it of the drive train and wheels for this build. I was going for a '70s Klunker look here.
I picked it up at a swap meet for $15 and the donor bike came from a garage sale, also $15. I didn't spend too much did I?