Here is what I know:

1. 1985 300CD California edition
2. 250k Miles, all service records since new, well cared for, zero rust!
3. Runs great, a little smoke on full acceleration
4. Has significant coolant leak on right rear corner of head (lose about 4 oz every drive), Gasket or cracked head?
5. Compression: 380, 320, 290, 360, 330
6. The # 3 intake valve has too much play in the valve-guide
7. Not doing this job myself, I have a Mini Cooper in full restoration and no way I am equipped to do two major projects at once. I thought I was done fixing this Mercedes!
8. Labor to remove, reinstalled, & tune whole engine is $5000
9. Full rebuild from Metric Motors is $9000 with freight
10. Labor to remove, reinstall, & tune cylinder head is $6000
11. Cylinder head rebuild is $4000 with freight

Note that the labor to remove and reinstall a cylinder head is greater than the labor to remove and reinstall the engine!

I am thinking I should go ahead with a full rebuild for two reasons. First, it guarantees the engine will have all fresh gaskets, so no rear main seal or other leaks to worry about for a few years. Second, the shops that do this work will soon disappear so better to get my "lifetime" car finished now than later.

The bummer is that I will have way more into this car than it is worth, but when was that ever not the case?