what does this line means? = "or utilize OEM pushrod length at least twice the crankshaft stroke."
in the rare case that you have a high camshaft engine, the rule makers want it to be able to run if the pushrods are long/heavy/springy enough to give the bike no rpm advantage (my interpertation). I cannot imagine an engine that could take advantage of this clause. No way the CG engine has pushrods twice the length of the stroke. Just concern yourself with the first part of the rule:
camshaft located at least one crankshaft stroke below the OEM cylinder deck
you should know the stroke of your engine. Measure down from the head gasket surface (cylinder deck) the distance of your stroke. If that point is above your cam centerline (and I believe it is), you meet the rules.
Done forget the big slotted screw you see on the side of the cylinder is the lower rocker arm pivot, not the cam shaft. The cam shaft is below the base gasket surface on a CG motor.