Since you are likely to have to trim say, 1/2 " off the mast butt to clean it up, why not raise the mast step in the bilge by that 1/2" with a non-corrosive plate (solid glass, or maybe "Star board" if it will take the compression). This will keep the mast butt out of the bilge water for a bit, and more importantly, restore the original height of the
rig so that your
rigging will tension back up again like it did before.
With older standing
rigging, that little drop in height might use up the free threads on some of the
rigging screws.