The flight international Archive is a good source of info, try this link:-

http://www.flightglobal.com/pdfarchive/search.aspx?ArchiveSearchForm:search=bac%20311&page=1&ArchiveSearchForm:fromYear=1966&ArchiveSearchForm:toYear=1971

The 2-11 was a kind of 1-11 on Steroids, it kept the single isle concept but unlike the 3-11 no metal was cut.