I decided to refit the Banks Europa fuel tank after seeing only 3 of the 4 mountings used, and the horror of seeing it hanging an inch below the bodywork. We tried to fit it higher today but couldn't get the 4 tank lugs to fit flat against the GRP bodywork. The lower forward one needs a spacer of 15-20mm between body and tank lug to bolt it in place. In its current position, the tank no longer sticking out below the bodywork. However, the tank's filler neck doesn't line up with the filler cap so I can't use the rubber joining hose. I'm out of ideas apart from the thought that the tank's the wrong shape, and the PO got a twin cam tank instead of an S2 item.
I've included some photos to show what I mean: