Welcome to the HazzardNet Tom. I doubt I can help you with the car advice but Hobie is right about needing deep pockets. 1969 Chargers aren't cheap. The question about being reliable depends on what kind of shape it is in. It would be no different than any other older model. Some out there run perfect and some are junk. It's like that old saying goes "You get what you pay for."
Unless you have Cooter Davenport skills and/or unlimited money to pay someone else to do the work you would be better off looking into prices on a 10 year old orange Charger and going from there. Wouldn't be a real genuine General but you could still paint General Lee on the roof, along with the flag and the 01 door numbers. It would be a great tribute car.
How long have you been a Dukes fan? Who is your favorite character? We're happy to have you here and hope to hear more from you.