Weber at Modern Muscle did a 454 out of a BGE block. Ran it in a Dart for Drag Week. Made like 850, I think. I forget the specs. Googler should be able to find it.
That's more of a "one hit wonder", according to what I learned from Dave Weber and others I talked to in 2010. Something like that won't last unless using the aluminum block. It's all in the extra reinforcement and the special steel sleeves to get longevity. I have a friend with a 449 cube, aluminum block Gen3 in an LX. Thing puts out over 800hp; naturally aspirated; no nitrous and runs 8.80s. Changing the cam soon, with expectations of 8.50s