I seem to recall reading in the Tower website tech notes a wing area figure of 681 sq in,

With the renewed discussion of this model I was inspired to get going again on my refurbishment project and am almost finished with the wings. Removing all those pinned hinges was a royal PITA. I made the ailerons a bit shorter and used the ends of the ailerons to make some proper Extra-type wing roots because the look of the full-length planks always annoyed me. Using the OS .91 with a Perry pump and tank on CG.