331cid sbf, solid roller turbo motor, mid .600 lift, std size lifters bores, ~650 lb springs. 7500-8000rpm capable. this is for a buddy, had some comps in it but on the tear down the lifters were harder to slide out on the wheel end, and there was scuffing parallel to the ears on the roller end and some in the lifter bore like they were spreading. needs to be upgraded, they have been in there for 4 seasons anyhow. any suggestions? whats the best? mostly track not much street driving at all.