If you're going to sleeve it anyway, I would just put the LS rotating assembly into the sleeved GSR block. You can swap the VTEC oiling components over to the LS block, but it'd just be easier to leave them in the GSR block and sleeve that. The VTEC oil pump would go into the LS block easily enough, but I believe there's some extra machining to do if you want to run VTEC oil squirters. Plus, you wouldn't need to have a girdle doweled in if you ran the GSR block.