Buying a classic car for a daily driver

[WalgreensDrake]

I've recently been thinking hard about what kind of car I want to buy - my old one broke down and was gonna be much too expensive to fix, so I totaled it and now I'm in the market for a new one. I'm certainly in no rush, so I've been browsing for a while, and I have come across a couple of classic cars that really caught my eye. They are priced super well and are in great condition. If I buy it, it will be my daily driver. What do you guys think about buying an old - but in great shape - classic car for driving all the time? I'm looking at a 71 Mustang, and aside from the obvious things like poor mpg or specialty engine work, what should I keep in mind, and what are some problems I could run in to? I would like a car that is fun to drive, but I don't want to make a bad decision that will cost me. I know it will be a lot of upkeep, and I know it won't be cheap, so if I'm willing to pay that, should I get this car?
I really appreciate any advice you can give, as I have very little experience with classic cars.
I have also heard that Mustangs are a great choice because they are popular and so parts are easy (relatively) to find. I saw some other threads about classic cars as DDs, but they didn't really go over the specific risks and things to keep in mind.