Just clean the cylinders well before you reassemble the system. Don't read more into the cautions about petroleum products and brake systems than is really there. The intent is not to mix petroleum fluids and brake-fluid. Light petroleum fluids like kerosene have been used as a cleaning fluid for honing operations since time began. If you insist on believing that the part has to be "surgically clean" before brake fluid touches it, then just swab it out with some soap and water and rinse it clear or wash it with lacquer thinner or brake cleaner or what ever. Also contrary to popular belief metal, cast iron included is not porous and will not soak up and retain fluids like a sponge. The important thing is to make sure you wipe it good and dry and that it's clean before reassembly.
Remember, common sense is not so common!
Denny Graham
Sandwich, IL
