318 Mopar vs. 340 Mopar

I am not going to rule out a 360 but I think I am leaning towards a 318. I am not looking to run the 1/4 for anything more than fun. I really want to just be able to have fun with it. I don't really drive much about 10 miles a day to work and back. and then to KC (about 1 hour) or St. Louis (about 3.5 hours) a couple of times a year. I am not worried too much about mileage but I still want to be able to run 65 for a couple of hours at a time without hurting it. I also know I will be replacing the rear end and the drive shaft. I know better than trying to use whats shes got.

If I look for a doner car are there any I should stay away from? I don't want a computer. thanks