I am nit a metallurgist but I work in the Railcar Industry and we by law must use graded bolts and give stated torque values for each bolt. We build the cars using a high tensile stainless. However, all of our critical fasteners are grade 8 plated steel bolts. In my own case I simply cleaned mine up and reused them for that reason. You can get graded SS bolts, but they are very expensive. For this application you can properly sized SS bolt and be fine. They are huge bolts, Honda did not kid around on those babies. I would just clean them and paint if needed.