So this project has been ongoing and finally reached near completion.
In the end I decided to use my original engine and frame from the above purple ZXR (so technically it's the same bike!)
There were a few issues with the wiring and fuel system but this has all been repaired / replaced and it is now running well and passed its MOT first time a few weeks ago.
Cosmetically I wasn't keen on how green the fairings were so bought some vinyl to break it up a bit.
The result is as below.
I've got a pair of zx6r mirrors to go on and a single seat cowl which needs to be painted first.
Other than that it's done... just in time for summer.