If you are going to turn a frank motor above 8k rpm there will be issues with heat/friction, and wall loading. Iron sleeves will help this but won't fix it. if you want the displacment and torque you get from the LS block just get a B18c block sleeved and bored to 84mm which will give you 2L of displacment. with that you will have a block that is made to rev to and above 8k rpm and still get the big displacement