Straub industries has a good utube vid on this. several sources say it is the gold std on this, that at half cam lift you want the rocker to be 90 deg to the valve tip/retainer THEN (at that point) you measure the pushrod length needed for however much preload you want. EDIT & Scott on the vid uses chebby stud mounted rockers & lowers them to get the 90 deg at half lift. & the chebby rocker choice for this needs to be right (for the correct wipe pattern) & you have yours already but FYI Mike at B3 racing is top notch for this. MORE EDIT I had a Q on the vid & the guy says to then lengthen the pushrod till you have zero clearance & I am wondering if it needs to be lengthened further for a certain amt of preload or shortened a bit for the cold or hot clearance for solids ???