There is generally always more wrong than originally thought. At least you still have the desire and ambition to keep plugging away.
My suggestion is still the same as it had been. Fix the brakes, so you can still drive and drive it. Then slowly work on the rest of the stuff. Safety items first. Brakes/steering/suspension.
Might want to talk to Rhinodart. He may have a parts car to cut the piece you need out of.
Mancini racing has a lighweight master with a small bore(I think) that I will be putting on my GTS. Idk if a-bodies have it, but b-bodies have a plate on the firewall for support.
Keep working!