If you just cut rectangular holes in the tops of some old covers, you will see what you want without oil flying everywhere to some moderate RPM's. Can't say what you will have if you rev to 5k, but the oil restriction in the cam system will keep the flow pretty low and mostly you will have just dribbles; it is the way it is designed. Mark your pushrods with grease pencil or welder's pencil just below the adjusters and it will be easier to see them spin.
