Last time I did guides the distributor stayed in place. BUT this could be an M116 vs M117 issue regarding deck heights. I also just replaced the tensioner rail liner. Unsure if MB still offers the liner for that separate currently.
I would rather a 30 year old, 100k+ OEM tensioner be in my vehicle than some aftermarket BS. Oh wait, that is what I did and now I am creeping on 190k.
Swag guide rails are good, I have used them in BMW M30s as well as my OM603 and 617. I would run them again. Iwis are the chains I use.