1991 300SE questions, head gasket, valves etc.

[unkl300d]

Hello my friend has this car with 157K miles on it(1991 300SE) . Previous owner has had maintainance work on it including new injectors.
However, my friend seems to have a bug up the B-Hind and wants to do preventive maintaince.

He was planning to have a mechanic replace the head gasket, replace the timing chain and adjust the valves.

Besides that he plans to replace the distribuor cap, rotor and spark plug wires etc. Tune up stuff.

He did not state any evident symptoms for wanting this work other than preventive maintainance.

He has no leak in the head gasket, and as far as I know, there is no significant oil burning.

I know the car has a bit of uneven idle but that is indemic to these cars.
My 300SE has this also. I live with it.

So, I did research in the archives and it seems the timing chain in this car is short and tough. So, perhaps it does not need to be pre-emptively replaced. ???
Does failure cause severe damage in these cars or just cause the engine to halt until part is replaced.??
Opinions?

Perhaps having the valve clearances checked may be a good idea but I told him NOT to have the head gasket relaced.

Often times you get more problems when you remove stuff than letting it be.

I told him that the timing chain could be replaced without removing the head anyway. He thought the head had to be removed for this job ergo the idea of having the head gasket done as well.

I told him that the timing chain cover half moon gasket leaks could be taken care of w/o head removal.

So, do the valves need adjusting or are they self adjusting???

He got a quote of $1800 for replacing head gasket, timing chain, replacing the stated tune up parts.
That is for labor only since he bought the parts already.

I told him to hold his horses until I got answers from this forum of noble experts !!

Anyway, please give me your opinions.

Thanks

Denis