Jan, it looks like the four pinwheel borders are sewn in place and this is the center of your quilt, ready for you to make the straight flying geese borders which come next.
If that is correct, is your concern that the middle part of the quilt is a little wavy? That waviness looks minor in the photo and will "quilt out", especially if you use a wool batt or a wool/cotton blend. Your measurement of 63.5" for the top and bottom pinwheel borders is spot on so you are good going forward. If your concern is that the top and bottom edges measure 63.5" and the middle measures 64", check the seam allowances all the way down to see if it varies. You would be looking to see if the middle area seam allowances are narrower and snug them up. Most of us have trouble staying 100% even with the 1/4" seam allowance, especially as these seams get longer.
The only way to make this perfect is to take it all apart and re-do it all, measuring everything as you go, as you mentioned a few days ago--NO, I wouldn't do that. Part of the beauty of this particular pattern/style of quilt is that it teaches us the tricks it takes to make a perfect quilt, measuring is very important every step of the way. But since "finished is better than perfect", I say, just keep going. As you make the flying geese border, check each unit for size as you sew them together.
I hope this helps.