According to EQ, for a 10" square in a square block the inside square would be 7 9/16" unfinished. 7-5/8 is 7-10/16, and 7-1/2 is 7-8/16, so each is only 1/16" off from the ideal size. That's probably close enough to make them both work, especially if you play with the seam allowance a little.