After filling a few bug holes I soaked the scales in neatsfoot for over a week. The soak at least fixed the twist in one of the scales.
Then I cooked them at 325 for 25 minutes between two steel plates. They are now flat, the pin holes line up, and they are ready for a final polish.
Thanks to everyone for your input.

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or vice versa if I didn't attach the pictures in the correct order.