^If they are willing to build another motor when this one cracks a sleeve/sleeves and your ok with being a guinea pig, then go for it. If not, I'd get another block sleeved and forget about this. Also, in EVERY ENGINE, the coolant around the sleeves usually flows into the head, then from the head, back into the radiator, and then back into the block. Thus flowing from the engine to the radiator and so forth. If you block off the coolant passages to the head, you'll have no flow and the engine will only be good for the track because it will only stay cool for 15-20mins before it reaches 210+ degrees. I'm not trying to be a dick, I just don't want to see someone lose money on a iffy modification.