The block has been bored out 20 over and we plan to use a b18b head so I am sure that the pistons need to be modified to match the valves. You have a good point (inspyral) about the Strength of the sleeve so a block guard will probably help us out a lot. Any other suggestions would be greatly appreciated. We need to look at every aspect of building this motor and it is very easy to over look key things. thanks