My Firebird/ Trans am is 74" wide from the outside of the flares in the center of the wheel opening. I have stock dented quarter panels but I stretched the flares 1" on each side.
Wow what a build, sucks about the setbacks. Can't wait to see it done though! I'm partial to second gens myself...
Have you already ordered the Anvil stuff? Seems it's highly unpredictable on when it will show up. Waiting on a hood/spoiler myself, no idea when it will come. Not sure if it helps that I went through classic w/ a 25% off sale haha.