We couldn't get the Comp hyd roller lifters to fit in this 340 resto block even after a ton of machining and grinding so we gave up on that idea. My next idea was to see if I could adapt the factory Magnum lifters over to this block. Close, but no cigar. With some additional machine work the Magnum lifters would drop in and work with a factory spider but we didn't want to put the block back in the machining center.