Remember - this is an OM603 engine, not an OM617. TOTALLY different animals!There is a specific reason I said to replace the glow plugs and vac shutoff valve. Both jobs are a NIGHTMARE with the intake manifold in place. It takes 5 minutes to R&R the shutoff valve with the manifold off, and 1.5-2.0 hours with it on - BT, DT. Ditto for the glow plugs - they're nearly impossible to access. With the head removed, it is incredibly simple to replace these parts. If they have 5-10 years, or 100k+ miles on them, it's simple preventive maintenance that's well worth the extra $100 part cost, which is negligible considering the job would be $3000 without doing those two things, or ~$3100-$3200 with (assuming a new head is needed.) There's no way I'd leave the old stuff in unless recently replaced! The intake manifold R&R is also several hours (with cleaing it up, etc).
I agree on the timing chain, if stretch is less than 2-3 degress it's probably OK. Changing it as preventive maintenance is a judgment (or budget) call.
The heads come totally bare, except for seats & guides I think. No valves or lifters. The lifters are common failure also, they collapse and "tick". Again, it's easier to have these replaced with everything apart, yanking the camshaft to do them later is not fun...