To ; upandrunning

Here's some more info to chew on;
The FWD 4.6 is not drilled and tapped for a motor mount on the pass. side.
The bell housing pattern is that of a Taurus.
The front cover is not the same as the RWD cars and trucks.
Those are just 3 BIG negatives to the swap you are thinking of.

As said before, the engine is good for it's internal parts but too much work and cost to be worth the effort.
Save your money until you find a 5.4 DOHC Navigator for a donor and buy the whole truck for it's parts 'cause you're going to need all of it and more.
If you don't you will be making lots of trips to the bone yards and the parts stores to get the things you thought you wouldn't need.

Been there, done that and doing it again.