[Jeb]

The 5.4L V8 is just a tall-deck 4.6L V8 (Holy Shades of Windsordom Batman!).
The 6.8L is just a tall-deck version of the 4.6L with an extra pair of cylinders cast on. As for the DOHC vs SOHC heads. Not that big a problem, though a little more involved than the old Cleveland/Windsor mountings (involving the front cover).

As for the supercharger, look in the valley area carefully. I seriously doubt they'd get 590HP from 427 cubic inches without one. The modulars have a lot of room in the valley and often feed the manifold from a blower located there (UP into the manifold). I believe some even manage to put not only the blower, but the intercooler there as well. With the added length of a 10 cylinder, the packaging becomes even easier.

It's still a humongous engine. The new GT isn't 43.5" tall instead of 40" for no reason. The 5.4L, with prominent supercharger (for cosmetics) is one talllllll engine.

The Ford 500/Galaxie/whatever is a tall car with a tall passenger space and correspondingly tall engine bay that could handle such a beachball of an engine. Supposedly somewhere mid-point between a mini-van and a sedan. The 427/7L designation is just another bow to the past recalling Galaxie 7 liters from the early '60's to the target market (why all the focus on a market that's going to buy at most one or two more cars in its lifetime is something I'd like to hear explained...maybe someone from Buick can jump in here...)

I am really tired of the Ford tease machine. I wish they'd actually put something out there, for a decent price, that shows they're more than a bunch of namby-pamby's.