Help identifying this NSU bike

 I'd like any help I can get identifying the model of this NSU bike.
I've looked at galleries of bikes but haven't found any that quite
match.  Either the forks are wrong, or the handlebars, etc.  The
photograph was taken between 1952 and 1955 in Afghanistan.  Can anyone
help?  Thanks.

http://www.dotrose.com/v2images/misc/nsu-motorcycle.jpg

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HLS