NG 45-2 Mount Everest and NG 45-1 Katmandu. Tiles of the Map India and Pakistan 1:250,000. Series U502, U.S. Army Map Service, 1955 (1954 China)
Cropping and annotation by uploader, own work.
The red line shows the road existing in 1975 and the black line is the route taken by the 1975 British Mount Everest Southwest Face expedition as described in Bonington, Chris (1976)       Everest the Hard Way, London:  Hodder and Stoughton  ISBN:  0340208333. .

The base map shows the then (indeterminate) border so the annotation shows the contemporary border from the Times Atlas/ Google Maps.
http://www.lib.utexas.edu/maps/ams/india/ng-45-02.jpg
http://www.lib.utexas.edu/maps/ams/india/ng-45-01.jpg
http://www.lib.utexas.edu/maps/ams/india/nh-45-13.jpg

http://www.lib.utexas.edu/maps/ams/china/txu-oclc-10552568-nh45-14.jpg
U.S. Army Map Service