I did some repair to my GTO lower "A" pillar. Pontiac called it the door hinge pillar.
I ended up fabricating everything, but it's all pretty flat stuff anyway. Mine wasn't too bad...the inner stuff facing the frame was bad, but the outer stuff was okay.
I have a webpage about this repair...take a look just to get an idea.
Squid's Fab 1967 GTO Body Work Page 2