Nothing on the R07 translates to the LSx engine. Nothing fits. Not the heads, crank, cam, nothing worth mentioning. GM says
Although the R07 is a purpose-built racing engine, it has strong ties to production powerplants. "The concepts and processes that are used to improve the performance of our racing engines is shared with the production engine designers to improve the efficiency of our production engines," said Tom Stephens, group vice president of GM Powertrain."
Which is newspeak for we want to tie it in to our production engine for advertising purposes even though it has no crossover.
The bore is not 4.5", the bore centers
are at 4.5". Big difference- NASCAR has a bore diameter limit at about 4.185".