Not sure without a picture. Are your blocks square, just not 8.5", or are they not a square shape or both? If they are roughly square, but not 8.5", you could find the smallest one and then trim them all down to that size. Normally, you would need to trim the same amount off all 4 sides to keep the block centered, but again, need a link to the picture of the quilt or a pic of the blocks. If they are just out of square, you can try ironing them into submission.