Put me in the "sacred cow shock tower camp". Just read this thread in its entirety. Very impressed!  I note that the export brace would have to be removed for the EFI IR setup. What structural modifications would be needed in its place? Jay (or others) could I trouble you for a quick rundown of your Mustang chassis modifications? Perhaps it's posted elsewhere? My Cougar is a ~20 year old restoration with mostly a stock 390 setup. The X Code volume was a little over 2037 units that year so not ultra rare. Plus it's been gone through once already and I doubt much can be reused. I like the idea of buying American and getting the best FE technology out. Mercury Cougar fiberglass hood reproductions seem sketchy too and I don't think I'd go as radical as the taller intakes would lead to.

Sorry that I don't have much to add to this thread but since we are in the technical section I'd like to expand on one of the tangents. 

The weight (lbs) per cubic feet numbers.... for air (vapor) and gasoline (liquid) do divide to 581 but that's exaggerated quite a bit. The only way I can think of to compare apples to apples (vapor to vapor) would be to recall that we want something like a 13:1 A/F ratio for max power. (Just picked a value - not making a claim) This is a ratio of air mass to fuel mass. So while still an over simplification (weight vs mass and an average per bank of cylinders) the 581 divided be 13 is more like 45. Still the gas is heavier and flow will differ. You get a "wet" intake with a carb/TBI but a dry intake with MPI since the fuel is introduced way downstream from the plenum. I don't know what to make of the wet vs dry intake condition other that a dry intake might be more prone to carbon build up. Can a MPI system with an O2 sensor in each header really adjust fuel per cylinder? Or is it limited to each bank of cylinders?

Neat truck. If you don't have one already is look into a fan shroud. Otherwise you've got advice from some of the best in the biz!