Get which ever car you feel is more fun to drive. I am assuming you like the way both cars look. If that's the case, then it all comes down to which car you will enjoy driving more.
Now, if you asked which car would I buy. I would take the money and restore a '67 Mustang GT convertible (It's not enough to do a Shelby)
Have fun with which ever car you choose, and remember, baby the paint, not the pedals