Thanks for the info. So bushing the lifter bores is not necessary if you restrict thru push rods? I do know the lifter bores in a KB block are a lot taller that a stock block. I just trying to figure out why you would want to restrict oil to lifters? I'm kinda torn on bushing the block due to cost as for it is another 600$ on top of a 7k block. I just want to do it right the first time as for the KB block is a new thing to me. There is a lot of opinions on this so I am trying to sort thru them. It will be a 4.5 bore 3.9 stroke solid roller motor that will turn some rpm's. I would think the geometry would be perfect in a new block from KB and I do understand the chances of failure and a lifter coming out of the bore and loosing pressure. So it appears the main reason to bush with a small hole in bushing is mainly to protect from loss of oil pressure if a failure happens correct? I do also plan to run a bushed roller lifter rather than a bearing roller lifter if that is worth anything. Thanks