The answer is 'Balls' Norm! ....................................Yes the item is the original, but I have added the dome to it.
Back around Xmas, I observed some Kiddies Ball shaped tins that contained chocolate of some kind. Managed to get hold of a couple and found one without any significant damage. Measured pretty close to the radius, so went for cutting a slice off for a test.
First job was to clean off the paint/ink to see what the finish was to the steel (top left).
I then had to polish it and measured the amount needed to slice off for a sample and what method to slice it off with ( bottom left)-
First go was 3/64"(1.2mm) short, so went for it on the good cleaned off section -
Cleaned up and tinned with solder, it was soldered to the original, which was not easy as had to use passive resin flux, but went ok.
Had a good coat of fuel proof lacquer and settled for an old small cafetiere s/s gauze filter cut to fit as a dust collector. All done and will go nicely with the now very tidy Carb.
Regards