Ooooh! I love appliqué borders on pieced quilts.
If you are flexible on size, you have a lot of options, but math will be required. Your starting size is 66” square. I assume the “logs” are 1”.
1. Decide if you want a square quilt. If so, something like 96” x 96” is pretty close to a queen size. If you don’t want a square, you will need to make larger borders at the top and bottom. It is certainly doable, but requires more math.
2. If something like. 96” square will work, the borders will total 30”, which is 15” per side. That might mean a skinny 2” border, an 11” appliqué border and a final 2” border.
3. You can test those dimensions by created an 11”x 11” piece of graph paper and cutting out some paper leaves and flowers to test a possible design. Once you are mostly happy with how it looks, lay it next to you quilt center, leaving a little space for that 2” inner border. If it doesn’t work, try a different width. 9”x 11” gives you a 3” skinny border above and below or a slightly smaller finished quilt. Play with the dimensions a until you have a good feel for your appliqué design.
4. Do the math again. A 2” skinny border will make the appliqué border 70” wide (plus corners at 11”x 11”). You can still work in block units, but instead of doing 11” by 70”/6= 112/3” each, try 2 11” wide and 4 12” wide units.
5. Draw your final patterns on graph paper.
Have fun!