Doug, does this checker provide a guide to rocker arm roller patterns or geometery? You know the valve stem wear pattern? I have never used one.Use your stock push rod and the blue checker along with a feeler guage set to get your proper length. Just install like a regular rocker and stock pushrod (7.800") add feeler guages (shims) to get the proper length just add guage amount to 7.800 (or whatever you're using) and done.
Put a clean smooth layer or two of masking tape over the rocker stud. This will remove the 'play' of the blue plastic geometry tool and give you an accurate reading.I put it on the rocker shaft last night, didn't think it fit very snugly at all. I bought actual adjustable pushrods for checking as well, not sure which I will rely on, or both. Gonna try to get started with it today. Don, I too am not sure how you go about determining the wear pattern on the valve stem. Keep me posted if you figure it out, please.