its been done before, but unless its more of a GOAL, or something you REALLY want to do, and dont care about what itll take or how much money, its not worth it at all.
And im guessing you mean fox, it'd be kinda hard to fit a 4.6 engine in a 5.0 engine
it's been done, and it looks awesome. but you've got to imagine very little traction, a very heavy front end, and many, many headaches and expensive receipts along the way.
if you really have your mind set on this, find a donor car. buy a salvaged gt or cobra and do the transplant. it will cost you a small fortune in misc parts to do the swap any other way, not to mention the time you will spend fabbing or hunting down said parts.