No change is sound when loosening the injector lines. Any issues with the internals of the engine are not too suspect. As the source of the noise. As regards the pistons and bearings.

Chase one problem down at a time is less frustrating. I would locate the noise that disturbs you first. Sometime an extra set of ears from a friend can help.

A very incidental thing to remember is to make sure the boost line to the turbo is clear. Later at some point. You get an old car that has just been driven with nothing really done. Even for decades sometimes. It can be a chore to get it all.

Sounds like fuel starvation either from linkage issues. Or the overall fuel system needs going over. Takes more time than money usually to do that.

Something that I have never bothered doing. Removing the fan belt could reduce the background noise somewhat. As an aid in finding a noise I suppose. Running the engine with no water pump working is not going to hurt it for a few minutes at idle.