China Coast

The map below shows the South China coast between Shanghai and Hong Kong, and the location of Gray Dragon Island.

For finer detail of the coast itself, there's a high definition 1950s map in the University of Texas collection here:

http://www.lib.utexas.edu/maps/imw/ Sheet NH51, which shows railways and roads (but note, it's 7Mb)

And if you fancy visiting Hangchow (Hangzhou), there's a 1920s guidebook here.