I don't know Justin, maybe a '56? The book I have shows that '55 still had the rounded style chainguard. Then it jumps to '57 where the chainguard juts forward in the front (see scan for view of chainguard). The one in your photo shows the chainguard swept back. Just a guess, but the bike looks like it's last half of the '50's.
It's a nice bike but If you were looking to sell it locally and the market the way it is, you'd be doing OK if you could get $150 out of it, even with the two speed.
Just my 2 cents, that's all.