Some of the things I was wondering about before I call Mitchell for more information. Wanted to know if the Lifter bores were bushed from Mitchell or does this cost more for him to do it. Also what bushing is used in the lifter bores if there is a clearance problem with the Link Bars then maybe a key way bushing might be better for the lifters. Is the push rod era on the block opened up for bigger push rods. I was told the the Edelbrock.Hemi Heads will be ready soon. Also like you I am listening for someones experience with these blocks. I am looking at building a 572, friend with a world block has a 604 built years ago with Stage V street head and a 630 roller shaft and made good HP with it and has had zero problems with it over the years.