With everything now in place I could continue.
Rear panel being tacked and screwed into place.
Corner gusset fitted and corner section
Rear wing fitted.
Nice and straight finally.
Getting the above straight and the corner section to line up took an incredible amount of time, measuring, measuring, measuring and head scratching over several days. The problem all stemmed from the replacement rear wing being a slightly different shape from the other side. It was only a few millimetres different but more than enough to throw everything out of line. Originally when I had everything in, what I thought was, the correct place - the corner light cluster fitted poorly and wouldn't make a seal. I even wondered if my cluster was bent and sourced a replacement to try. When that didn't fit I really was lost for a while.
Anyway, with that and other issues beaten I was on to the finishing stretch.
Bonnet on, panel gaps perfect, lights in and bumper on.
One straight rear end with no bondo!
That brings me all up to date again. There's a few welds to clean up on the rear end so that's the next small task. After that I'll be venturing under the sail panels to see what rusty delights are awaiting me.