You'll need EA-EL rocker gear and cam. AU is different somehow, can't quite recall how though. I do remember that AU cams/rockers won't work in an E-series head and vice versa.
Still got the XG XR motor? Use the cam and rockers out of that, I think I read somewhere in this thread that the XG XR6 cam was the hottest factory cam used in the E-series/XG/XH 4.0, with the EA 3.9 cam second.
Have a read of this thread, it should tell you everything you need to know