Hmnn. I could never make a living assembling engines............
When block is received back, before anything else, every hole inspected and chased, every flat surface touched with a flat file to check for burrs, any gasket surface not showing bright cast iron wet sanded with emory and oil using care not to round off any surfaces. All passages cleaned with a brush. Blow through every oil passage and verify. Test fit cam before any other assembly. Cylinder bores washed with soap and water until a white cloth comes clean. Every bolt wire wheeled. All clearances measured. I expect piston clearance maintained within .0005 cylinder to cylinder. Usually test assemble the rotating assembly without rings to verify piston protrusion, rod to jet clearances etc. Meanwhile all the time I'm working on this, my clothes are clean, I blow my clothes off before entering the area, engine always wrapped when not working on it and no passages left open for anything to get or fall into.