Nice project, but a couple of notes...
On that model, they usually have ABC suspension, think Citroen SM. On speed. With a computer.
On that car specifically, the red display in the cluster is not good. Could simply be down to a 'dangle berries'ed battery, but the picture isn't clear enough to guess.
Also no MoT, but the ad is honest enough 
Otherwise, what could possibly go wrong 
Im aware, and slightly scared about the ABC issues, although I believe that has its own dedicated " ABC fault, drive carefully" light.
I have even begun preparing for it on the off chance I end up buying one.
http://mercedes-abc-drive-carefully.blogspot.com/2014/08/overview-abc-system-isthe-key-part-of.html
Circa 360bhp would be fun though for that sort of money. If all else fails, bin the ABC and bung a set of coilovers on it.
That's a handy link

Also, occasionally, the dealer books crop up on ebay, not cheap, usually £100+, the Introduction to Service ones give alot of useful things like specs and system overviews, but the system specific ones are about as thick.
It's the leaks and component cost that put me off ABC, a valve body is £1,800, there's at least two.
Mine had/has (it's intermittent) an Airmatic fault. Turns out to be a sensor. Mounted in the engine bay and held in with two bolts... I will deal with it in due course.
The airmatic system can be replaced for about £1,200 as a worst case... 19 bolts, 12? air lines and four grub screws, so a solid day's work.
All that said the Coupe is a good looking car in the right colour... Looks stunning in a black cherry metallic, but like the Omega, you can generally get them in any colour you like, as long as it is Silver
