A little update for today.
Bent up and rolled the new arch pieces for the drivers side arch and tacked them together.
Its made from 18g mild steel.
I trial fitted it after tacking and it fits very well so should be no problem when it comes to welding it in place.
Ive also mocked up the other side and cut the pieces out today so they just need bending/rolling and then Ill tack them up, trial fit them and then weld both new arches up properly ready for welding in place in the shell.