Check out panel print quilt designs to see how they spaced blocks and set them off with different sashings/blocks. Random sized blocks would be interesting. I like your idea of batiks that go with your sepia print. I'd use a see through template to fussy cut fabric, selecting area you want to highlight. You will lose some scene as you cut out and focus on a section-can't be helped. Very unusual fabric and I'll bet your FIL will love the quilt.