I have no dog in this fight and this whole build may well be a figment of the OPs imagination. But an engine doesn't know the source of the boost that's helping it make horsepower.
A quick check on the Turbo forum will show a sticky of a professional build using mostly Ford GT engine pieces. The purpose of the thread is to show how to make north of 2000 horsepower. Granted that you'll be able to get more boost from a really scienced-out turbo installation than from any centrifugal blower, it's still easily possible to get more than 1000 HP from a 4.6 with a Vortech and the other necessary hardware.
KS