So first some more CAD
Tacked in place and rear edge replaced
The end result after flapper wheeling I think is quite good. Pity it will never be seen as will be covered by the front edge of the rear quarter panel
At this point I decided I wanted a proper spot welder before continuing as the next step is to fit both outer sills.
So while I looked for one to buy I had a look at the the front chassis leg / arch / bulkhead. It didn't look pretty.......