Measuring pushrod length in Magnum engine

[Siksty7 Dart 270]

I'm working on a stock Magnum engine with a reground cam. I'm measuring for new pushrods. What additional length do I add for proper preload at zero rod lash? Should preload be added to the maximum pushrod length at zero lash (valve fully closed and lifter plunger all the way down)?

 

[Siksty7 Dart 270]

Disregard, I found a video put out by Melling. I will be measuring the plunger travel dividing it in half and adding to the length of the maximum pushrod length at zero lash.