Classic/Antique Car Repair: Classic Mustang Purchase to Restore, ss chevelle, pony interior

Question
Hello,
My husband is traveling a fair distance to look at a Mustang for me that is either a 1967 or a 1968. He has done restoration work on Chevys (completely restored a '66 SS Chevelle) but is unfamiliar with Fords.  Can you give me/him any advice on what to look for when he goes over this car? Are there any places on Mustangs that are notorious for going bad? The car has been sitting in a field for 5-10 years but the glass is all there, the paint looks good, and everything original is still in the car, even the pony interior. He is going to pay $500 for it. Does that sound fair? Thank you for your help!

Answer
Under the best of conditions these Mustangs would rust and you would end up with a moon floor. If you are in the desert then rust is not a concern but if you are in the northern tier of the country be carefully of rust. They do make replacement panels for Mustangs but it can get to be a lot of work. Remember that this is a unitized body meaning that the body and frame are all one piece and rust attacks it all.
Brad