we do restorations and modding.. it is very hard to find a mustang that old that is not a rust bucket for the kind of money you want to pay.
most of the time they need full floor pans, trunk pans, and shock towers...just for starters.
even the 66 fastback we bought for 4500. still needed floor pans and trunk pan. and the torque boxes almost always have to be replaced.
we have done several of the 65-66's now we are looking for a 67 fastback to do an eleanor clone.
I'm willing to take on a little bit of rust, plus I'll probably be looking all over the country--it's easier to find rust-free or less rusted cars in the Western half of the states. Hell there was another 69 coupe that sat in a wrecking yard for years in my hometown ... I never had the money to bring it home ... it had a bit in the quarters but was reasonably clean. I think the guy sold it finally for like $2000. Wish I hadn't missed out on that one.