Clearance between the rockers and the spring. I,ve bolted the same rocker assy to the original 587 heads with similar results. I,ve read all the geometry stuff and think mopar has always been off a little
It's just the rough casting on the armpit...
Kind of the nature of the beast when casting stuff.. some are going to be a little different than others but the relationship between the adjuster the push pad and the massive hole for the shaft should be the same... (But I'm told they're not LOL..) again this problem generally happens when putting larger diameter Springs on...
And personally I couldn't give a flip trickle about perfect geometry.. I would rather enjoy my mopars driving them and racing them then letting them sit because of not perfect geometry.