Some more progress pictures of works to modify the seat back position. When the original support is removed there's a couple cover pieces that need to be rivetted or bolted in place to hold some loose ends together, and provide a better visual appearance.
I've finished the left side and centre section covers. Just the right side to go.
Match drilling the new left side cover piece
The centre section cover piece in place
Riveting the primed and painted left side cover in place