Was able to get a reasonable finish be soaking in Pinesol for a few days. Then used a wire wheel in an angle grinder to clean surface and get the fresh aluminum surface. The wheel left a little grainy finish, but was able to get a more uniform pattern with a little experimenting on the angle, speed of pass and direction of the brush rotation and hold time. Then used a stiff manual wire brush across any graining to remove the rest of the directional grain. Looks OK. We then coated with a clear finish to keep it from oxidizing in the future.