Personally if I was swapping a 6 banger Mustang to a V-8, I would lose the entier front suspension and swap in a Mustang II style from suspension.Get rid of the shock towers and you have a ton of room. Put in an 8.8" rear end. Disk brakes front and rear. Then I would go with either a 5.0 fuel injected with a T5, or a carbed 351 Windsor.