If there's any video that will let you hear the Trackhawk's 707-hp powerplant in a number of different situations, this video will be it. From (legal) city driving speeds to full throttle on the track, lots to pick up here.
I would essentially look at the Demon bottom end and see. They didn't change the heads, but everything else got bumped up so it would be a good idea. It also helps to look at other builds and see how you could achieve the same power elsewhere