i'll throw in my 2 cents. I look for a narrow sweep, not a centered sweep if you are doing the sharpie on the valve stem and turning the engine over. the wider the sweep, the more waste of lift, and from what I understand, side loading of the guides. I made a tool to measure the sweep across the valve and its really eye opening to see what a pretty insignificant change in pushrod length does to the width of the sweep. that being said, I don't have lot of experience with shaft rockers, primarily sbc and sbf stuff is what I have done. but im working on my first shaft motor so I am looking forward to seeing how what I have learned applies to these engines.