Brake cleaner is great, but is very expensive. Get a tub if you dont want to buy a parts washer, fill it with 10 parts kerosene to 2 parts engine degreaser, make sure you have a lid so it does not evaporate. Use that to clean the parts, along with wire brushes and then scotch bright for the machined surfaces, then when the grime is gone use the brake cleaner before you paint. The brake cleaner removes all the loose dirt and oil and is the absolute best thing to use before painting.