what about copper plating several coats then if needed sand to fit the outside diameter ? ,i had an acquaintance who had some severely pitted bumper guards for a 1959 356 a porsche ,they were no longer being made so he had the fellow at the plate shop dip them about 10 times in copper he then sanded them flat on both sides with a block of wood and sheets of wet or dry <black sand paper> until he had the pits worked out this required several trips to the plate shop until he had all four of them perfect .they were then chrome plated and looked better than new .the plate shop owner told him how to do this but said it was too time consuming for them to do it .but that he could do it if he chose to hand block and finish contour them then he could get a nice job using just his labor