Whatever you do....don't get a 280SL.
The plot thickens.
Yesterday after I put everything back together and started the engine , the tic was there but much quieter. After about 10 minutes of driving the tic was almost all gone... that and the lack of fan roar made driving a pleasure again. Later that night, I went for a nice top down drive. The tic was almost completely gone and life was good. Then on the way back home the tic came back with a vengeance... just as loud as before. WTF!
When I had the covers off I took measurements of all the thrust washer thicknesses, the deviation of each valve and the cam lobe height. All the cam lobes were almost exactly the same so the cam is off the table. That leaves compensators, rockers and shims (and the valve itself).
It has always sounded to me like the tic is coming from the drivers side but I can't be 100% certain, but based on my measurements, the drivers side thrust washers are almost all 5.1mm but the passenger side has mostly 5.45mm thrust washers. And again... most of the valves on the drivers side show a sleight minus deviation. When the .01"mm steel disks arrive on Monday I'll shim all the 5.1mm thrust washers on the drivers side to eliminate the minus deviation and I may even favor a sleight plus deviation. If that doesn't work I'll do the same to the passenger side and if that doesn't work I have on last desperation move to try. Read on...
Last year I bought a used drivers side rocker cover. If I'm out of options, I'll cut the top of the rocker cover off so I can see the rockers in action with the engine running and without spilling oil all over the place. I have run the engine with the oil fill off and watched the oil stream down on the cam but I didn't ever see much oil splashing. Even if it does splash all over when I cut the top of the cover off, the cleanup chore will be well worth it if it isolates the offending valve. With the top of the rocker cover cut off I should be able to isolate the problem to a specific rocker and take remedial action on that specific rocker/thrust washer/cam lobe combination. It that fails... maybe I'll try a 280.
p.s. I read somewhere (I don't remember where) that at some point, Mercedes modified the go no-go gauge sizing to produce additional preload. Maybe my gauge is the old style and I'm not giving the valves enough preload. Just wondering.