If you have any kind of metal finishing shops near you try this. I found a shop that does different kinds of metal cleaning/shot tumbling. I had them clean the bell housing on my fmx, they glass beaded it then tumbled it in steel shot. After that I coated it with RPM and it turned out fantastic. Even did it to the power steering pump bracket. PM me if you want more details, I could give the number to the shop and he could tell what to look for.
Chris