I recently aquired my fathers bike which has been sitting for 20+ years, did some work and it runs great but now after a teardown of everything but the engine block I have run into a slight problem I canĀ“t find a cost effective and fairly easy way to remove the corrosion on the cylinder heads and cooling fins, I would really like to not sand them since its cast, I will polish them once I can remove this tough nasty corrosion, any suggestions?