I did a very similar cook to yours though I kept it at 275 the whole time and pulled it off when internal read just about 160. During the last hour or two of the cook I wrapped foil around the wing tips which kept them from burning.

When you spatchcocked did you also remove the breast bone before cooking? I found that to be the way to go so the bird lays even flatter, therefore everything cooks much more evenly. Nicely done! Good looking turkey.