Metal engine parts go in the parts washer.
In those, you typically use aggressive petroleum-based solvents - that's why the parts washer has a lid that flops down - to suppress fires! Companies like Safety-Kleen will even supply you solvent and exchange/freshen your solvent from time to time and dispose of it properly.
Myself, I like the idea of using B-100 Biodiesel, which is at least semi-green. Though the stuff you are soaking off the parts isn't slightly green. It also isn't much of a detergent and that is a property you want.
I generally have a coffee can and a tray inside the parts washer, which I fill with solvent as needed, and leave parts to soak for a few days if possible. Then I use non-metal (nylon) brushes and dish-gloves to hand-clean.
I would not use metallic brushes on any critical surface like gear faces, certainly not using a power tool! Once the parts washer has done all it possibly can, I have been known to wash off the solvent with thinner or carb cleaner and let them dry, then clean up non-critical surfaces with metal wire brushes or a beadblaster, and even prime and paint. However I do this quite reluctantly, because I do not want to destroy any factory treatments or anti-corrosion coatings. Going to town with a wire brush on a plated bolt will get you a rusty bolt.
Lubricants have two roles. #1 to keep it from rusting while in storage, and #2 to protect it during assembly and initial engine startup. If you don't know what to do here, then that is a "red flag" that you need to do some more learning on the subject of engine rebuilding - maybe get an actual book, which will serve as a well-rounded primer on the subject. Google only answers questions, it doesn't tell you which questions to ask.