I believe you have the newer engine
shock mount method shown as on the right of the drawing in the
link and the enlarged diagram below.
Check to see if that is what is in place, before you decide to order any of the engine shock system parts.
Item 29 is the rubber fused to metal shock mount that tends to fail (123-241-48-13), and that's the costly one.
Item 65 is the repair kit (123-586-06-24) which is reasonable in cost.
The kit may have changed as the diagram seems to have some additional components that are not in the PP kit, and there is no bolt in the diagram either.
If the rubber/metal engine shock mount is shot, I wouldn't get the repair kit nor the rubber/metal shock mount.
Removing, replacing or keeping worn engine shocks and mounts in their current location won't affect the idle smoothness.
Again, IMHO not an essential system, I naively replaced them on my first MB (an 83 W123 300D), and it made no difference except for emptying my wallet.
For the OFH (Oil Filter Housing) to engine block gasket, only get the original MB waffle weave gasket (616-184-07-80)...accept no substitutes.