Wow, another guy who kept his favorite car from the 70's. Finding out theres quite a few of us. I've had my 67 since 79. Picked up a 68 GTO few yrs ago to restore. All these yrs i've never owned a GTO, but probly gon'a have to sell it to finish the FB's. Worst part is, it's the most solid body muscle car i've owned.
I've been luck with the rust issue. I stole the Firebird from Brett's (1stgenbirdman) part of the country--Washigton State, and he was kind enough to look at it with me since I'm mostly a dumb GTO guy.
About the only rust in my Judge is on top of the rear end and the rear springs where both of them were not painted. I have used naval jelly to remove the rust from the top of the nodular iron center section--it took a couple of bottles to get it all off. Most of the frame still has the factory paint on it and some undercoating so I'm just sanding it down my hand and repainting.
Some day I'll get a nonoriginal engine Bird and make a hot rod out of it if the purist in me will allow it.........................................