Your welcome Max and I agree, a great forum! I've learned a lot about my ticking issue and am leaning to the worn cam theory, mainly bec. idle is somewhat uneven at times, but quite mild. This could have been avoided if the previous owner took action when it was ticking only at start-up. All the more reason to take a look at it now.
In your case, I think it's rocker arm or shim related.
There's a recent thread from another 560SL owner you might find interesting: Camshaft wear on 560SL