As a Ford dealer tech, I can tell you that your little "project" will NOT be a cheap proposition. To get a PROPERLY working V10 3-valve, you're going to need the PCM, transmission (Torqshift), all associated wiring, as well as the necessary plumbing needed to convert your existing return type fuel system to the returnless style that is used on the 3-valve engine.

Now, HOW MUCH of a challenge are you in for?