So,after much messing around in Photoshop,I finally chose this tail piece

It's off a 1990 Ducati 900 superlight,very luckily one was on Ebay at the time.

XBR light fitted easily enough.Now the hard bit,fabricating a seat base and battery holder,many hours later this is what I have come up with.



and now with the tail piece fitted

Still got a bit more detail work to do here,but you get the general impression-oh and I don't like the red,probably paint black/white latter.