so has anybody attempted this type of nightmare?

From what I can tell it doesnt seem "all that bad" to do the swap....the only real challenge is the intake manifold, and if you know of a competent machine shop that can fab up some 1/4" manifold spacers you can use the 4.6 2v manifold on the 5.4 (I'm making my own 2v spacers out of a 1/4" sheet of phenolic resin I bought online...it cuts pretty easy with a die-grinder and is heat-proof)

Do You Think That The Phenolic Resin Will Hold Up To The Heat And The Pressure Of Torqing The Intake Bolts

these guys have done a few, with some good results. www.mmperformance.us

they did a 5.4L SC from a lightning into a 97ish GT and then another into a 2000ish GT.