First off, they are already supercharged. You will never get to 700 HP with a 5.4L, you simply cannot rev them fast enough. They make GREAT Torque, but are limited by their long stroke in the HP department.
VT engines can handle anything you want internally, but even with the best tuning around from SCT, and forged internals, it will never make 700 HP and stay togather.
Boost means nothing, except that the supercharger/turbocharger is trying to push more air in than the engine can injest. What you REALLY want to maximize is FLOW.
Boost does not really hurt the rods, RPM does. Boost will kill pistons due the the added heat associated with increased boost, which leads to knock.
www.vtengines.com
www.sctfalsh.com