Either way, that's a nice bike and looks like the buyer got a good value.
My quess, it's a fairly original 1970 Roadster, repainted. Looks like original downpipes and early Black tail piece.
Which, just in my never to be Humble opinion has the sexiest add of them all.
View attachment 112517
I think you'd be right on all counts
I've tried and failed to source original shape downpipes. I have an original pair but they're in need of new chrome.
There's an assumption that all Roadster pipes are the same, but it isn't the case.
I wonder if these cleared the kickstarter?
The new A-N 'S' Type seat repros are the only ones available, and as LAB has pointed out, are different to the originals - in this and other details.
There were none available when I built my '70 Roadster; the rear profile is all wrong, but I remedied that after this photo was taken.
The 'S' Type had a wide top, slab sides and thinner padding, and followed the profile of the frame to mudguard transition, banana seat style, while the early Roadster seat used the same base, but with thicker padding tapering towards the much narrower top.
The seat on the Mecum bike above just looks to be badly fitted, thrown on for the photos, or possibly bent, as they were prone to fracturing (see below). It has the correct side profile, which was unique to the R, 'S' Type and early Roadster.
The beautiful studio shot posted by MichaelB shows the curves very nicely, I think
Comparison between a NOS 'S' Type and very shabby early Roadster seats - so both are 'original Norton' - there's a U shaped strap welded across the nose of the seat base, visible in the photos. In reality these bases are pretty flimsy and broke easily - see the Roadster seat pan behind the mounting lugs.