The problem is, even with a good looking body, these cars are going on 30 years. You need to assume that you're going to have to rebuild the engine and transmission. In fact, my experience has been that the transmission only last around 70K. I'm sure others have had different experiences, but two of my cars, one with auto and the other with manual, needed transmission rebuilds just around that time. My daughters 77 has just around that mileage and the transmission feels like it will need a rebuild soon.
On the engines, they start leaking oil from that rope seal about 70K, and they need rebuilding before 100K. I know there are cars that differ from what I've stated, but assume you need to do those things so you won't be surprised. Don't assume you can buy a 30 year old car and not put any money into it. So, if you get a sound body, you may have to have it painted, but you won't have to deal with the rust issues...that will save you money.