I bored and sleeved the cylinders on my C-60. I used bronze when I did it and they have been trouble free. I also bore and sleeve Amal carbs as well for english bikes. There is an ongoing debate between stainless and brass and bronze. There are many different types of each material. I have used some of each and have found if you do a clean and complete job with each they shouldn't be problematic. I run a gunsmithing shop and am a firm believer in the quality of the job sometimes is 50% or 75% the man and %50 to %25 the material. Thats just my 2cts. Good luck either way.
