Yep sounds like chevy builders doing that will tell you if your rocker to valve tip geomerty is correct but the length of the pushrod will NOT do anything for it since you have a SHAFT MOUNTED system and once you bolt it down and torque to spec it is what it is. You have to use spacers under the shaft OR remove material from the cast stands to change that relationship.

Has the block been decked alot ? heads shaved alot , head gasket thickness vs. original ? These are things that aeffect the pushrod length on big block and small block mopars .