The easy thing to do would be to find a whole setup from a 98-05 f150, expedition, excursion for a 2 or 3 valve 5.4/4.6. Althought the "trick" thing to do would be to find a navigator or an aviator to rob. The navigator has a 4v 5.4 and the aviator uses a 4v 4.6l similar to the Cobra. You would need the harness, pcm,engine,trans,radiator etc. A lot of places are now building performance parts for the 5.4l such a Sean Hyland. The BIG problem would be if you wanted to keep a manual trans with the new engine as ford uses the pcm to also control the auto trans, so you may have some software issues with it. You can by-pass it by using a F.A.S.T. pcm but that system runs roughly $1800 + dyno time to tune the calibration. You have a lot of options, just depends on how much you want to spend.