So chances are, I'm in your dad's age bracket (I remember how my teacher reacted when JFK was shot). We all remember how cool certain old cars were. As a big DIY guy, even back then, I also remember stopping 2 miles from home to open the hood to pry the choke open to keep the piece of shit running. And I remember that all the odometers were 5 digits because virtually no car ever got much beyond 80k miles before heading to the junkyard. And I remember how quickly old cars rusted out in the great salt belt to keep winter snow at bay. In addition, does your dad know about hardened valve seats? Because if a 70's car is all original, it depends on the lead in gas to keep the seats from self destructing and guess what......there's no lead in gas anymore. And of course, all 70's cars need the carb adjusted with each passing season. Around DC, the seasons change....right? If he's not a DIYer, then it's reasonable to set up 4 appointments a year with your local old car guy to re-adjust. Speaking of carbs, you do understand that even a small block V8 in one of these cars is going to suck down about a gallon every 10 miles, right? And on street parking? Well, expect the little dings from kids on bikes and people sitting on it and who knows what else.
Personally, I love the way old cars look. But compared to cars of today, they are garbage. Younger people simply have not experienced how much pieces of crap old cars really were.