A friend of mine restomoded a 1966 'stang, it looked incredible relative to where he started with it. He put in a modern 302 and transmission and upgraded the suspension and brakes, and it still drove like crap. It was fun to be out in on a nice day (not a rag top), but it really didn't drive well at all, in my opinion (and he agreed).
It's also surprising how slow the 60s muscle cars were in comparison in acceleration in most cases. My other friend's Jag was original, it needed some cosmetics work and he thought the engine wasn't really pulling it's worth but he worked on it a lot.
that said, I think one can have fun with them, just don't expect some great driving experience.