NYC , I only posted within this post yesterday ,see if it can give you some more help . https://www.benzworld.org/forums/w140...take-leap.html
If this car you like has a good paint & a nice clean unmarked interior , its a serious car to look at , as I mention over & over again ,mechanical repairs are not a big issue until you need to change for a new engine like I did ( but I knew before purchasing mine ) , the one job I hate on 140's is the evaporator leak , look into that more then anything else ,struts can be changed easy by yourself all around the car ,changing bushes on the suspension arms etc are more of problem because you need a press or the trick if you do it your self (there is a trick without using a press ) .
Sometimes when owners of this type car don't have the service booklets or records ,they did all the work themselves obviously like me for example , the only things I cant do are things like wheel alignment or other mechanical work were there is a need of a specific machine like AC refill etc .
Working on a V12 engine is fairly easy ,don't be scared you learn as you go .
Check the small narrow space out between the radiator and fan ,once you pull up the cross members 3 screws on each side ,the radiator moves forward giving you some space ,remove it completely & that space is huge giving you access to water pump , steering pump , fan clutch & everything in front there including engine belt .Changing spark plugs is a breeze in compared to others ,everything think else is the same like any other w140 .
If you have a black interior ,parts are all over e'bay for that colour combo ,Tan/Beige & lighter colours except typical common grey is more harder to find interior parts for .
Read the link above now and what colour is this car & interior ? .
LWB250 Dan above gave you a real good advise ,I like it .