This is a half-century-old wheel cylinder. Corrosion, rust, deep pits, and wear suggest replacement with a new cylinder. Years ago, honing was an acceptable practice for very light surface blemishes and stains. By the early '70s, the practice of honing gave way to removal of minor surface stains with crocus cloth. Use alcohol (denatured or isopropyl) to clean the cylinder. Never use mineral-based oils or solvents near rubber parts! If working around grease or oil, wash hands thoroughly with soap and water to prevent contamination of rubber.