Rockers twisting and rubbing guideplates usually indicates a stud that's either bent or intalled at the "wrong" angle. If your valves have at least 1/4" above the locks, you can discard the guideplates and use "rail" rockers (later model Fords and Chevys have rocker s with "rails" to keep them centered on the valve). It's important to understand, only ONE method of "alignment" can be used. If more than one, it WILL "bind".
It's also possible, when the heads were machined for screw-in studs, the "slots" used to guide the pushrods weren't "opened". They should now be about a 1/2" diameter hole, NOT a slot. That too, WILL cause "bind".
Lastly, be certain the pushrods are "hardened" for use with guideplates. It will SAY SO on the package or in the product description. Generally, if not noted, they're NOT hardened.