I did a test assembly of one of the uprights to check proportions. The vertical supports (thanks, Ron) seemed too beefy. I went back and looked at photos of the original for comparison, and my supports are definitely thicker. I know that the thumbnail edge that I'll be adding to them later will visually make them appear thinner, but even so, they're a bit too thick.
Back to the drum sander. With luck, I can use a light touch and get rid of the burn marks. Win-win!