I'm still out there working...
More rust found on the bottom of the door...
and repaired...
More sanding! I have to give praise to the How to guides on
www.mig-welding.co.uk for bodywork, especially the ruler trick and also a tip I found elsewhere of adding a bit of fibreglass resin to the filler to make it thinner.
I cut a metal flange piece which was bolted to the body, the remains of the Kamei was then bolted in place and the two bonded together with fibreglass filler. The ends will be reshaped and the whole thing smoothed before I use it as a master to create a mould for a new fibreglass part.