Hello there I'm and old Diesel Mechanic, and I have worked on everything from earth moving machines, cats, Detroit Diesel, Cummins, International and the Benz, that is my speciality. I own them and work on them, Number one what condition is your engine in, has the oil been maintained if so do you have any oil leaks. no leaks , Mercedes has a pretty good real main seal if it is not leaking I would do anything to it, now does the pan leak? if so you will need a big tube of gasket sealer this is a special sealer from benz use only this it will set up like a gasket should and seal. now for the Injectors you can get the parts to rebuild your own injectors pretty easy or you can get rebuilt from the dealer. as far as WVO use a good filter system preferable a heated filted in the trunk and one in the eng carpartment. order a kit from greese car that is what I use, Timing chain you can do that job also connect your new chain to the old one and feed it in by turning the eng over slowly until the old chain is out then use proper tool for fastening master link. adjust your valves properly. you can replace all the valve seals before you do the valve adjustment and adjust each valve as you go threw, make sure you put the right seal on the right valve, intake or exhaust the kit will tell you what is what. I rebuild engines all the time. Especially Diesel. Good Luck need help let me know. Jerry