Use 5 inch blocks and put 2 inch sashing between the smaller blocks. Put several lines of these on each side of the 8x10 to fill out the width. Rows above and below the picture and 5" blocks can be larger blocks with even different size sashing between. Cutting out blocks with pockets and off-center fronts with buttons will add character and interest. I have even seen some with an embroidered block with his name, birth date, marriage date and death date. If he was in the service a block of his unit would look great. As long as the horizontal sashing size is the same width the sashing between blocks can be smaller to make the width of the quilt come out. Using pre-washed flannel makes a loving warm quilt.
Debi