I would check to see exactly where the bores are at in relation to the crank centerline as well as each other (oposing 90*) and in relation to the front/back of the block (for/aft spacing). A real race engine machine shop can put the bore EXACTLY where they should be for maximum efficency and performance. If you must use that big a bore size and its gonna be thin AFTER correcting the bore spacing/placement, I would sleeve it but only after the bore is centered where it needs to go. Personally, I run a way smaller bore size and have no issues/worries about thin cylinders and it works for me. 8.92 @ 149.95 mph 2900lbs 360 inches N/A no power adders...