I'd go with mid '60s.
Neighbors had a '49 Westinghouse that was identical to ours, and replaced it with a new frost free top mount Norge that looked very similar, but the handles had the more common angular look. The fan at the back of the freezer section would cut out whenever the freezer door was opened.
Considering it's all there, $100 isn't too terrible. That fridge will likely still be running after we're all dead and gone.