Kiwi,
I think what R was saying was there was more frames than the Garden Gate & dual front-tubed McCandless designed Featherbed, it could be my fault, I could have misread the article, often motorcycle stuff is not written that clearly.
However, personally, I am never sure about stated,(published,) originality of machines at certain periods of time in firms, manufacturing history, especially when models where in a transitional period & especially when bikes where exported models, as they often differed from "cooking" more bland, less "blingy" Home market stuff.
However, you have the history of the machine, but especially, after the War factories were notorious for using up parts on certain batches, post -war Government restrictions often dictated slight changes & of course owners often changed & upgraded machines with, better options, sometimes later parts from the factory or specialist after-market stuff. The main thing non-originality hurts is value on resale & also as a talking point at meets from knowledgeable experts!
Norton Owners Club is this best place & I suspect R is a member.
Photographs are brilliant, looks like a good purchase, for me sometimes originality can be a bettered, but it depends on what you want and if you want it 100% original, go for it. \the main thing is to have FUN!
Cheers
JBW