Hughes Stainless Steel Magnum rockers

I've heard a lot of good things about Hughes rockers in general but haven't found much about their stainless steel rockers for Magnum heads in particular. I was confused at first because I didn't see in pictures any adjusting screw on the pushrod side, then I read the instructions from their site saying it's all done by the hold-down "nut" and the little allen screw that holds them in place. I'm assuming with these in order to get proper geometry at the needed valve lash/preload the pushrod length is extra important?

I don't have any experience with roller rockers and still have stock stamped rockers on my Magnum-headed LA 360, at $345 these seem like a good value. Not looking to put these on anytime soon though just wanna get a better understanding.