A can of gasket remover or oven cleaner or aircraft paint remover and lots of scraping and elbow grease can be used to clean the iron parts of gaskets. Don't get any of it on your cam bearings or it will eat them. I like a wire brush, nylon bristle brushes, gun barrel (oil galleries) brushes and tooth brushes too. I use varsol and then laundry detergent to clean it up, followed by the pressure washer.
Here is a danger. If you don't get every lick of water off the block you wll have rust, so I finish rinse with very hot water and dry everyting off with rags, flipping the block over often to dry everything. I pull clean gun patches thru the oil galleries and then finish with patches of Fluid Film rust preservative and a light spray of the block. This will hold it while waiting machining etc.
After machining I go through it all again but it is much easier and quicker. You can assemble the engine with clean hands.
Steve Best