I put the Clifford aluminum cover on mine. I had to tap two holes in the head on the carburator side. They were already drilled or cast in the head and only had to be tapped (I think that they were originally locating holes or something like that). You'll need a tap that will cut all the way to the bottom of the hole as they aren't drilled very deep and if you try to drill them deeper you will drill into a water jacket. Don't ask me how I know that.
'86 CJ7, 258 w/Mopar MPI, 4.56 gears, rear Detroit/front Truetrac, full cage, OBA, 8274, 4" lift via Alcans/Rancho, 35's on beadlocks, other stuff. Built for rocks, mud is a four letter word.