I've read here and at other sites that there is a possibility of a larger displacement, higher horsepower engine scheduled for the C-6. The most popular speculation seems to be that Chevrolet will continue to use the LS-1 block, but increase the displacement to 6.0 liters. Some say that they may even go to a 427 (~7.0 liters) out of that block, which I believe is near the maximum for that engine, but that may be wishful thinking.
FYI: The C5R has a 426 cid engine in it, and this uses the same block that is in the "civilian" Vettes. Seems like the technology is there to me. Wish they would employ it for us, too.
Oh, well. I love Corvettes any way I can get them.
LMN8R... I believe Lingenfelter created a 427 (428 really) based on the current block. But the cylinder walls were less than paper-thin. He had some hi-tech sleeves in the cylinders. It was reviewed in a 2001 Car And Driver issue.
Chevy, in 2001, created the Tigershark protoype in the 700hp range (for some reason, 745 sticks in my head.) I have the article at home if interested. I don't know if it's ever been discussed around here. Probably.