Thanks very much for this excursion 
For other interested readers I’d recommend these image series; many of above mentioned details can be seen here:
http://www.classic-motorcycle.com/Terrot-HST-1930-350cc-1-cyl-sv-a-30/mobile/
http://www.classic-motorcycle.com/Terrot-HST-1930-350cc-1-cyl-sv-a-25/index.php/