I would go for the 79, even if it weren't a 10th anniversary car as long as it had a 400 or 403. That 10th anniversary car is worth quite a bit. What are the asking prices of both cars? I remember when they came out with the turbo's. I was disappointed that they went to the trouble of turbo charging the smaller engines and eliminated the bigger engines. I would have preferred a turbo charged 400. But with what was happening with gas prices and emissions controls, the bigger engines were doomed.
The problem with paying a premium for low mileage, and the premium is quite high, is that once you start driving the car the premium disappears. But if you plan on making it a garage queen, the value would be retained.
In the mid eighties you could pick up a low mileage T/A for three or four thousand dollars. I remember going to a car show where they were selling cars and thinking...why would I ever buy a new car?
But whatever T/A you buy you'll love it.