We have seen this as well its not per say a name brand pushrods more so the size the 7/16 size in many case will make contact with the tube and in some cases no amount of work to the tube will correct this.. We have our made in a 3/8 for that very reason. With a 700 lbs load rating they get the job done as others just with out an noise issues.
This is issue is even not just about cam or milled heads ( that will effect it ) but being these are production engines you get variance from one to the next.. My own 2009 had issues with the rear EX.. During cam testing I had 3 sets of quick installs I tried all would hit on the rear with tube work completed. Cams from 255, 48, t man 625, woods 9B, S&S 585 625 and the crane 296.. ONLY on the rear ex.. Different heads , rockers and all .. Bugged the crap out of me.. but testing is all about time when you are working on the dyno for back to back testing..
Glad you got it sorted out.. The ticking can drive you crazy ..