I finally hit 270k miles. I just performed the following work:
1. Resealed the upper camshaft cover. The DIY article on this site was a huge help. As noted in the article, I used Hylomar sealant and it worked like a charm. My 86 300E had a 6mm hex on the rotor drive (instead of the Torx noted in the article). Also, it took some gentle persuasion to remove the rotor drive from the camshaft.
2. While doing the above job, I replaced the valve cover gasket.
3. Replaced the distributor rotor, cap, Oring, spark plugs (HR9DC+) and plug wires.
4. Replaced the air cleaner filter and some vacuum hoses.
5, Changed oil (Mobil I 15W50) and filter.

I still need to replace the transmission filter and fluid and flush the brake fluid. I probably should replace the valve stem seals, but I am waiting to see how much fixing the cam cover leak helped.

All in all, the car is running great!

Brent