I've talked to Hinson and he was trying to get LSx into an 8. But I don't think he has done it yet...
Cost, it will be 7-12k, pending motor.
But the problem I might see is how the motor will sit (renesis sits very low) and the LSx ems will work with rx8s ems which controls abs, traction, etc..
But at the end, LSx 8 vs older Z06, you aren't getting much benefit... FD vs. older Z06, at least you have the weight advantage, but not with the 8.. I guess if you want to be cool with V8 under instead, I guess i could see that
But I would rather just go out and buy an Z06 instead the headache of conversion... Few FD V8 owners have done that after their conversion... go out and buy the original that came with the LSx engine..