Welcome to the site, Neal!
It looks like you'll be busy with that '74 Challenger, but it will definitely be a cool car once it's all finished.
Judging by the rust around the vinyl top molding, I'd say you'll find some additional rust under that vinyl roof. Fortunately, they're reproducing most of the panels you'll need and the quality is 10X better than they were when all you could purchase were the quarter panel skins (mine looked awful when I bought them 6 years ago).