As far as I know the stamped steel rockers from 78 to 93 will all bolt on and work. I have a set of unknown vintage, 78, I think, bolted on my 94 Lightning GT40 iron heads. Has Comp Cams valvesprings and runs to 6000 rpm every time.
This is with a cam with a hydraulic flat tappet cam with .484 max lift.
The Cobra roller rockers are, obviously, different. The stock type rockers that are found on the Explorer heads offer no performance advantage over stock Mustang rockers.