To start, stop worrying about sanding. Get some Formby's Furniture Refinisher and rub the stock down with it. That will take the gunk off and show you what else needs doing.
Sanding will be virtually non-existant.
Wet the dings and apply heat: A wad of wet paper towel on top of the dings heated with a hot air gun will pop out most dings. Let them dry before sanding lightly or you will take off "plumped" wood which will then cause a hollow when dry.
Those two steps will do a tremendous job of improving the looks of your stock.
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