I like the four blocks together but I would point the butterflies outward instead of inward then I would use a 30's era fabric probably a solid or two color (not a multi-color fabric) for a sashing.
If you want the quilt bigger I would still put the four blocks together to make a big block and alternate with a large solid block of 30's fabric then use a multi-color 30's print for the sashing. In the big solid blocks I would have my quilter sew a beautiful butterfly design.
Can wait to see what you decide to do with your friend's blocks!
Angie