IMO you would do better to have the rusty bits cut out replaced with new metal and then paint just the rear quarters. It worked for my GTV as you saw at NAD and will probably be cheaper than new panels that if they are not original will need fettling to fit properly.
That's the plan Peppka. The outer wings could be easily patched this way as there's only small bubbling, however the inner wings have become debonded around the wheel arch due to wet mud trapped behind the arch, the inners have rotted and the tricky bit would be mending the inners without destroying the outers gaining the access. Must get the rear liner off and have a looky.