I don't think you're going to make 400HP with that set up.....maybe maybe 350. The problem is that you haven't addressed the engine internals. Your engine is like a long tube...you can ram more air and fuel into the front, and enlarge the back, but what about the middle?
You know, for that chassis, 325-350 is more than enough, if you want to drive this on the street. And you'll need to think about suspension and brakes, too, and no doubt frame stiffeners, etc.
You have to carefully plan projects like this--if you just bolt on stuff from a catalog you're not going to be happy with the result, in my experience, even after spending lots of $$$.
For even less money, you can get a normally aspirated CRATE ENGINE with a warranty, and about the same HP.
You might also call up THESE FOLKS to see if they can reach your 400 HP goal for you. Notice what they do to the engine internals to get this type of power.
Also if you don't rebuild and strengthen your 5.0 now in your car, I think the supercharger will shortly destroy it.