I believe that the screens are listed by Autoglass for replacements.
Wishbones should be able to be manufactured by any competent fabrication shop or try Fibre-Form/Dave Sewell who made much of the original Ginetta chassis.
the "lucky" part of the damage is that you can upgrade now to the G33 wishbonbes with the possibility of adjusting the camber. i´m not sure if you need new uprights though.
G33 wishbones are about as hard to get as G27 ones. I have just tried to source some after a bit of an incident. The upright is even harder as it was a Ginetta only part and according to Spadge the moulds have been lost. G27 upright is Triumph so is much easier to do