Dockboy's up there as far as #'s go... I think he dyno'ed at a max of 756 on NOS, and puts out under 600 on #2. I spoke with him, and I'm not sure he wants me to repeat this, but basically he is getting tired of breaking bottom ends which cost several thousdand dollars to fix each time.
There is a guy in NJ who's online handle is "Thuglike" and IIRC he out did Dockboy on the dyno, but not at the track. I almost had the oppurtunity to meet this guy, but he never showed up @ the track last fall. Hopefully I'll meet him August 11th @ the track.
Cale's truck @ BTS is the fastest fullweight 7.3 afaik, but it's an OBS single cab that runs 11.5's or better. He's dyno'd beyond 756, but I'm not sure exactly what his #'s are.
Unless you have 30k to spend - don't push your motor that far. Chip it, injectors, turbo's, other bolt-ons and stay away from the giggle gas!