63 Valiant Convertible Purchase

Hey, I am considering picking up a 63 Valient vert, going to look at it this weekend. Any advice on what to be on the look out for? My brother had a 73 'stang that developed a bad case of "sway belly", and I'm not looking to repeat that. This will be my first droptop, so I'm not sure what can go wrong, how hard it might be to fix, or when to just walk away. Any input would help....