Fuel cap arrived today, £130 including shipping and import duty. very large and very nice.
It won't fit into the fuel cap told that Chris supplied. I've just cut it in half an added a 20mm strip, not perfect but it will do me. By the time the cap is fitted I think it will look fine.
Side view, this will be 5>10mm lower once it has been bonded under the shell.
The measurements of the cap are
Base plate diameter 120mm
pipe inlet diameter 51mm
cap diameter 110mm
cap measured flat to flat 165mm
Needed to do another cut at 90 degrees and let in 10mm to get the cap to sit properly.