Wheel cylinders can be bored and relined with either brass or stainless steel (stainless is better), so don't discard yours. Just about any machine shop should be able to do a pretty good job of reconditioning a wheel cylinder, but some of them are reluctant to take on a job that requires a lot of setup time on their machinery, and relatively few parts produced once they're ready to go. Look for am old retired geezer like me with machine tools and such, and be patient while he tinkers!
Jerry
