Edward Turner of Triumph visited Japan in the 1960's and his verbatim report here makes interesting reading. Not strictly sandcast related I know but gives a good insight into the demise of the British bike manufacturing industry in the late '60's.
The Edward Turner article scans are quite big so I have added to 'Dropbox'.
Hope you can view OK, let me know if you have any problems.
https://www.dropbox.com/sh/h7gwhdcesqsy9s6/AABWGK0eMvErNbJosSR0gbQlaCheers ... AshD