So, if you're recommending replacing all of the exhaust valve stem seals, and all other seals (and the head gasket and crack inspection with 289k on a #14 head?). Sounds like a rebuilt head is required.

Noise: started it up cold this morning and it sounds pretty normal for the first 5+ seconds, but it doesn't fully smooth out and purr, and smoke is evident almost right away. It continues an intermittant quiet clacking. If I hit the accelerator it smokes more and the clacking gets somewhat louder. Sometimes it clacks more loudly. It does not take "a few minutes" for the clacking to begin. does the valve job address the hydraulic lash adjuster(s)?

If the noise is unrelated: Heim ends look and feel OK, but I don't know how they fail. to I'm going to postpone removing the serpentine belt, as I may get an indy involved or help confirm the noise diagnosis. It is fairly ellusive and changing.

I can replace the water pump and Heim ends (inspect and clean the turbo/exhause man for oil. Anything else? replace timing chain?

By the way, the local MBjunkyard called to report the 87 sedan's engine ($1700 installed) has 254k miles and compression is 320, 340, 380, 360, 360, 320.