Sorry but I don't follow your logic. Are you trying to avoid drip timing an IP by putting in a new chain? You should really check begin of delivery after replacing the chain.

Do you have access to the factory service manual (FSM)? Chapter 05-320 is your man!

If you want to correct for chain elongation then I'd go for the offset key - although I don't think I'd bother for 4 degrees => from my calculations the MB key is a bit out at the lower degrees of elongation

OM617 (non turbo) cam profile specs, piston height specs etc

I think an offset of 0.49mm is required not 0.7mm - but anyway there's nothing you as a DIY mechanic can do about that discrepancy => you can only choose to use the key or not.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!