Wow - this thread is an oldie for sure.
My answer is you an old Mopar is fine for a kid IF they have the respect and personality to match. My first car was a Challenger at age 16 so I'd be a real hypocrat if I said no. The main thing is they need to be responsible for their choices. My parents made me buy my first car and pay for everything. I grew up always making better choices because it hit me in my own wallet. By the time my younger brother was able to drive, my parents had more $$ and they bought him everything so he "did not have to worry." Well, guess what, his first car got wrecked pretty quickly as did his second and third. My first car left my possesion in better shape than when I got it.
My two boys are already planning on having old Mopars as thier first cars. My 10 year old wants a Roadrunner and my 7 year old wants a Duster. I am already planting the seeds that they will be responsible for the cars. Not only that, I am telling them they are going to have to buy them, so, start saving now. Both are planning on helping build their cars themselves, so they will have plenty of sweat equity in them when they are finally able to drive. NOw, I am sure their cars will be a lot better than my first 71 Challenger was, but hopefully, they will have enough respect for their cars not to be stupid with them. If not, they will hand over the keys for a short time. If it becomes a "problem," the cars will get sold or put away until they are responsible enough to treat their property properly.
That said, in today's market, your best value is a A-Body.