For anyone interested, for this quilt, the blocks finished at 8". I cut the center sections at 4.5" x 8.5" and the outer rails at 2.5" x 8.5".
If you do chain piecing, you can cut the outer rails as 2.5" by width of fabric and chain stitch the center blocks to the strips.
There are 48 of the blocks in my quilt (6 x 8).