[W126 Coupe] Camshaft replacement

[Andrew Sporner]

I am told that the right camshaft needs to be eventually replaced
(makes a clacking sound when the motor is cold and their are grooves
on one of the cams)  They tell me that the car can go up to 50K Kilometers
more without problems -- or die next week.

Can anybody suggest the level of difficulty.  I am not foreign to working
on cars (rebuilt the motor on my 1976 Ford mustang -- though admittedly
I sent the top-head away to get remachined).

I suppose you just have to mark the gears on the timing chain and just
replace?  Or is there more magic involved?

Andy