bes built 807hp out of a 5.7 with ported 5.7 heads more than 5 years ago on pumpgas. check out engine masters winners to check that out. it was a 407" i believe.
This 449 was originally built by BES and initially produced 711 hp. It was run in the car for just a short while and then went back for a bigger cam and more head work for more hp, but I forget the number. It was put back in the car and the aftermarket rocker system failed. It was then re-built by another shop in NorCalif; heads tweaked even more and I believe the cam was changed again. Then it was sent to Ray Barton for final tweaking and tuning. I think it put out more like 820 hp. (I got the initial 711 mixed up with the 8__ number. Initial couple runs ran 9.56 (ran 9.53 back when it had 711 hp) with traction problems off the line and half way down the track. He was feathering the throttle toward the end of the track. The engine is built for 8 second zone and we're waiting for better weather to get there.
I remember a high horse 5.7, but don't remember it being quite that high. Consider though, that engine was built for a dyno competition. It wouldn't live long in a car on the track...