In the aftermath of an engine failure

I have started my hobby as a mechanic by purchasing a car (too expensive to be a hobby car) that turned out to have a cracked head. (2.5 l CRDI engine)
Oil mixed with water and finally water with oil. Dismantled the whole thing, pulled the head, hoisted the block, dismantled it allthe way to the crankshaft and pistons level. (At that level I brought it to a machineshop to be cleaned and machined, also got a new head for it also cleaned and resurfaced.

Now my question is:
When dealing with all fluids mixed into a milkshake mode, how much do I need to worry about all the external components like turbo, radiator etc. BEFORE rebuilding it all in place? Do I need to go through all of it or just use a cleaner liquid of some sort when starting with it? Oil needs a change after a while anyhow but the turbo oil ducts and the whole coolant side is my worry.

I have the block and the head assembled but separate, as it is way easier to lift the block in by itself instead of trying to drop the whole package in on a one go. Just because the torque converter housing was a pain in the *youknowwhat* to remove even with the head off the block, I imagine it would be even more difficult to install with it on..