Polish them there rocker pads on a wet stone, like you use for your skinning knife. Just drag them down the wet stone covered in good honing oil until you have an um-blemished surface with all the wear marks gone. Probably not as good as new, but you end up with a nice fresh flat surface for the cam to break into. I tried it as an experiment and it worked just fine.
I used a fine grinding wheel on a 20R engine.....................
I've heard (not personally) of the rocker arms tapping against the valve cover....................
