I've seen worse. Do you have the front clip parts (fenders, hood, radiator mount ,etc?) It looks as though it either came from a junk yard, or somebody was using it as a parts car. The first thing I would do is yank that engine and get it going. Most likely it will need an overhaul. After that, I start rebuilding the body, starting with the engine bay. That Mustang can come back to life, just take your time.