This Guy did it and posted a lot of really good pictures of the build... too bad it's in a different language.

Sladdprojekt W123 -83 OM603 Mynä. Nylackad och bromsad! - Sida 10 -


Even has some video....

https://www.youtube.com/watch?v=lmmqXeUBJGY

Even more... it's a beast...

https://www.youtube.com/watch?v=RZOxTlH3AVo

From my experience, replace the intake gasket... for that matter replace them all while it's out. Also, replace the front and rear main seals on the engine while it's out and easy to do. Check my 87 build thread, right after I got my engine in the car the front seal went... PITA. Pull valve cover and check the lifters. There is an updated design for them now. Focus on keeping that engine cool... that #14 will crack the first over heat. Good luck with the build, look forward to seeing it!