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.