2012 GTI Engine replacement: What to do at the same time?

[MonLand]

I am DIY'ing an engine replacement on my 2012 GTI w/DSC gearbox.
While I've been DIY'ing everything for many year, replacing an engine will be a first for me.
The replacement engine is similar mileage to the one that died (~120K miles).

I'd like to know if there is a good pointer to:
- What to do to the engine -before- installing it?
* Rear main seal?
* I'll open the oil pan to peak inside, verify there is no crude
* I'll pour some diesel to attempt to dissolve any carbon deposit on the piston rings (I think this is what killed my old engine as it kept running out of oil and.... the drivers were not good enough refilling at every gas tank fill up)
* Chain guides? (that one I think I will do by default since that seems a wear part of those engine and easy to do if engine is out)
* I'll check the turbo for play, but I suspect it is in great shape
* anything else on the engine itself? (I will swap out a few parts like water pump, EGR "block" since the ones on the old engine are less than 10K miles)

- What else should be done/check while the engine is out?
* clutch friction plate/disk?
* anything else?

 

[alpha3]

Replace timing chain and tensioner?

 

[MrFancypants]

I’d do the timing chain assembly, water pump, and rear main seal. Also have a look at the clutch.