I know you said you are powder coating your swingarm. I think that is ok, but check out if it changes the surface tension of aluminum. I read an NTSB report from a helicopter crash one time where a control rod had broken in flight. The cause of the accident was the annodization of the control rod. Evidently, the helicopter was a pretty custom show chopper, and the owner had all the control rods annodized. the annodization actually changes something in the aluminum's surface structure and caused the control rod to lose about half its strength. Considering the abuse a swingarm takes, it might be worth knowing if that will affect the aluminum.