I think the grey looks fine with it. I used to only use cotton batting, now I'm hooked on Hobbs 80/20. I love it! It sews up as nice as the Warm & Natural, but has a nicer drape to it. It's also less expensive. I would have to audition colors for the binding, but at first glance, I'd try a green or blue. If you don't have any fabric to audition, try other household items like towels or tablecloths, something like that just to get an idea of how it would look at the edge. Take a pic and look at it a bit before you decide.
Antique machines are not scary! They are usually much simpler to use and sew nicer than the newer ones.