The HUGE difference between the VooDoo and the Ferrari's is you have to be very careful with the balancing of the engine itself. Mostly why Porsche, Ferrari, etc only went to certain sized motors on their flat plane engines. Ferrari went from 4.5L/4.6L N/A motor to a 3.6L twin-turbo on their V8's. The 5.2L is probably the biggest displacement ever put into production for a flat plane crank V8, and Ford had to do quite a bit of R&D on the balancing before feeling confident enough to sell it. These motors are meant to be revved high, and that is where its power benefit is.
Also because of the even firing order, you may not see the same gains from exhaust as you would with the traditional V8. Also, not sure if it is true, but Ford did claim that even their exhaust played a part in balancing the motor out.
As Manuel said, it probably isn't going to be 200HP+ gains just by throwing FI onto the motor. It would be interesting to see what you come up with, but just be aware, these engines aren't like what most of us are used to in relation to modifications.
