I'm planning to do a "deep clean" on my engine and part of that is to clean carbon / gunk from the piston faces and cylinder. I was planning to use WD40 and a slightly abrasive cloth like a green pan scourer, as well as some shop wipes. I was also planning to inspect and clean the coolant / oil channels and re-tap the bolt holes.
I will not be removing the cylinder block from the engine however, so this will be done whilst it is in the car, with the pistons still connected to the crankshaft.
My concern with this is mostly around WD40, coolant, metal particulates etc. getting into places they shouldn't. To mitigate this I will be taking the sump off and, once I'm finished up top with the pistons, inspecting the underside of the cylinder block and trying to blow any hidden contaminants out with compressed air.
Is this a good plan? What other precautions should I take?