I am in the process of replacing the timing chain on my girlfriend's '10 justa. It has about 90,000 on it, started making the death rattle.

Current additional things I'm replacing:
Belt Tensioner pulley (13 dollars for just the pulley, tensioner is fine) -> bearing had play
Friction wheel: I have a URO part on the way, but will attempt to replace the bearing in the original one, as the bearing had play. I may transfer the URO pulley into the OEM assembly.

Other parts that might be relevant:
Water pump: Bearing feels okay, no leaks. Is it worth replacing this now, since I'm there, vs should I wait till it fails?
Water pump drive wheel: original dayco part, in good shape, with plenty of smooth "tread" left.

 

Some also do the oil pump chain whilst in there. If not done I would replace the water pump with a metal one instead of original plastic, if original then it is reaching a fair mileage and while you have the engine mount undone, you can access it more easily by lifting the block, it is a real pain doing the pump with engine in place. Drive wheel/unit should be good, I did not bother.