My personal guess would be a Spaceliner older than this '63- It just says "1950's" to me-
By the 1960's big tanks were pretty rare except maybe a small one fixed around a light
and the 'snowflake" style sprocket is something that was generally used earlier- a european influence that disapeared when they cranked out more and more through the years- you could replace that with an annodized aloy one- search on ebay.
Also- what about the tires- do they say 26x 1.75 or do they say 26x 1 3/4? A clue- generally I think it was Schwinn used a tire labled with fractions- or am I confused?