600hp? Although that's a huge increase on the standard engine, there's a naturally aspirated 6.3L (stroked to 7L) in the galleries (Mechanical section) that was reported to make the same figure, although it did have 8 throttle bodies.... I'd suggest this car would benefit from an intercooler and larger ducting, but the biggest problem is a lack of room.
Oh and I've heard of several XR6Ts making over 1000hp....