Depending on the shell all are ok for the period as far as I know. Many early bikes have seems to have the rim with this fixed thing for the screw. I would take that one for your Norton if your shell can take the corresponding threaded lug in the bottom. Nice find.
Bottom left is indeed a black out mask with the centre removed. I had a job lot of 6" rims made from masks. I suppose after the war its was a quick and cheap way of getting rims.
Hey Kostas have the footrests arrived yet?
Cheers, Mick.