valve lash measurement

[chargerdon]

On my small block 360, with stock Rocker arm shaft and rockers.   Im about to replace the camshaft (with a lunati voodoo cam).   Lunati says to make sure the valve pre-load is between .020-.060 inches.    When i do, can anyone tell me the easiest way to measure and insure that the Pre-load is between that on our non-adjustable rocker arms?   

[Cuda Cody]

@Chryco Psycho   

[Chryco Psycho]

tough to do so on the lifter that is on the back of the lobe so you know the piston is topped out before you tighten the shaft , so when you tighten the rockers shafts down you can measure the depth of the piston in the lifter using a vernier caliper