I have a good friend that is a serious drag racer. He uses SBC roller blocks and buys all that come up. He knows what he is looking for and buys all that he considers worth while. He uses stock high performance Chevy lifters. He runs them for a season and changes them out for new. He has never had a failure. They are a fraction of the cost of Comps or others. I'll try to get him to join and share his knowledge on this topic.