There have been a few reports of repro tanks with pics, you may have to search for them. Not enough to make me jump in though. I'm not sure anyone has gotten the Roadster or FB partsparadise tank, there was another vendor though that got reviewed, but I think it was alloy. I was emailing the partsparadise guy and he seemed knowledgeable about the Norton tanks and would make one, even a metal one without the lips so it would look like the FG tank. He offered to make me one for around $300 delivered as I remember.
Dave
69S