I personally have never seen it done, however I don't see why you couldn't. You might get some guff about it but who cares? I sway more to the Cummins engines but like the Powerstrokes as well. My friend has a 6AT Cummins out of I believe a UPS truck in his, it isn't real fast but its a really neat engine. Looks like it grew into the truck too.
I am pretty sure at that point, it all boils down to the initial cost. If you find a Powerstroke for a smoking deal, why not swap it in? Also, they do have forums I bet for people wanting Powerstrokes in anything, I know there is a Cummins forum out there designed for people who want to put Cummins engines in anything I believe.