I guess you have adjustable rockers? If so measure from the lifter pocket without preloading the lifter to the bottom of the adjuster on the rocker with about 3-4 threads showing below the rocker. Then ad .040 to that number. Make sure the lifter is on the heal of the cam. That is how I measure them.
So is the .040 accounting for the preload? Is that why you add it? In that case, that would mean that every rocker adjuster has to be dead on exactly the same, right?
What I mean is that if I measure using the intake and exhaust from one cylinder, and order the pushrods based off those figures, I would have to go through and adjust all the rocker adjusters to be exactly the same even before installing the new rods - otherwise the preload could vary from valve to vale, right?