Unable to see if this was the actual 500 sold to Dunstall by Norton or a later one. As Dunstall never sold the original works engine it has very likely got the standard valve gear.
http://www.flickr.com/photos/59728935@N07/6064662146/
this pic shows the works engine;
http://www.etmoteur.fr/images/domiracer ... umn_93.jpg
