It looks to be a STD model since there is no Tank/Headlight or racks. (granted yes they might have been removed). my guess would be a mid 1960's vintage.

you may check out National Bicycle History Archive of America they can help identify the Year or the range of years. I sent them pics of a JC Higgins i have and since the SN# was missing a digit they were able to narrow down to a 4 year range 1958-1961.