Remember lots of Emerson Lake and Palmer is riffing on classical stuff. And Yes used to open their concerts with a bit of Rite of Spring. Premiata Forneria Marconi's William Tell Overture (should have been called "Blazing Accordions"). Maybe some King Crimson too, though nothing immediately comes to mind... Too much prog rock in my youth.
Great to see Jethro Tull's take on Bourrée in your list!