Just joined the forum, this thread is what hooked me in!
The BSA variant is quite widespread, we came across one in Portland IN, USA at the gas engine and tractor show in August, and have just picked up a pair yesterday to play with.
Pictures of the Portland unit are here:
http://www.stationary-engine.co.uk/P...tland08467.htm
http://www.stationary-engine.co.uk/P...tland08468.htm
That seems to carry a 1960 date tag after the 'BSA' on the label, I have a close-up shot of the label but didn't put it on the website.
We will be looking out for documentation over the next few months, and I'll get some pictures onto the website as we proceed with the restoration. Both look good enough to be repaired and got running.
Peter