Arguing over timing chains...Never !
Seriously, are you experiencing problems? I am at 105K on my 400E and my tech has specifically stated that a chain change now is not required. I would be interested in what you have heard.
As far as rails...If you are gonna do "it"..do it all. Tensioner, rails, chain....get it over with!
I understand that the chain on the 119 is the most durable part of the system. The tensioner and upper rails tend be be more fragile. I'd watch them more closely and if you are going to replace the chain, take care of all the support parts at the same time...