Daily driving an A-body
A few thoughts: Every old car will need some work when you first begin driving it. Unless you know the car's history, or have documented proof of use (service records, etc), assume the car has been sitting, even if registered.
Second, 65cudalover said these cars do not brake or handle in the rain as well as newer cars. A LOT depends on the tires. My '73 Duster is better in the rain than my 2002 VW, or my 1997 Jeep. The reason is the tires on the Duster have only about 3000 miles and are less than four months old. I also have disk brakes, which on the a-bodies at least, is a HUGE improvement over the drums. Tires are Firestone Indy 500's, by the way. I have heard T/A's can be slippery in the rain. Do research before buying.
About the break in ability, though, it's true. I have locked my keys in the Duster twice. First time (for any car) breaking in took me less than one minute (not including the time to twist up the coat hanger). When I park, I put any valuables in the trunk, out of sight.
I also have some money invested in my car. Guess what, I have spent more on each of my other two cars. And they are depreciating at a depressing rate. The lack of depreciation alone should more than offset the increased fuel costs of even a V8 A-body. My commute is 60 miles per day, I have been using my Duster since June, and I stand by this statement.