OK as i understand my block (5.3l) has the same bottom end of the LS1 block minus the bore size correct??? So if that is true that would also mean that the crank in my 5.3 should be 3.622 and in turn my rod length should be 6.125 correct???? So then the only thing diff would be the bore size, now my main question is are the actual sleeves diff in size or can my 5.3 be bored to the same specs that the LS1 can be bored to????

 

Stock iron blocks do not have sleeves and yes you can bore a 5.3 to a 5.7.
It's been done before by some of the F-Body guys that wanted to spray huge shots of nitrous. It's not very popular but, like I said, it has been done. Try doing a search in the internal section.

 

Our engine's only have 4 bolt mains and the LS1 has 6 bolt mains if I remember correctly.
Philip S.