Wow... they're even more amazing than the last lot!
It's becoming quite a mystery, I can't wait to find out more about these blocks, where they came from, why they were made, why they never quite made it into a quilt. Good luck with the search!
You're right about the setting, the pinwheel is too big. The idea of a fiddler also sounds nice, but may detract from the blocks and become a focal point. What about keeping it simple and using a nice musical print in the centre diamond? That way you bring in the music, without creating too much of an interest point.