I agree. "Hex" and "The Bees Made Honey..." are amazing records.
The fisrt recommendation that comes to mind is the obvious one that you've probably already thought of: Ennio Morricone. He scored countless Westerns and other films, including "The Good, The Bad, and the Ugly." I'm not sure who his influences are/were or which musicians he collaborated with, but he'd be a good starting point.
If you're not familiar with the band Across Tundras, they're another good reference. They play slow, doomy, atmospheric music with the same Western/Americana vibe as recent Earth material. I especially recommend their album "Dark Songs of the Prarie." If you like Earth, I think you'll dig Across Tundras a lot.
Oh, and a guy named Jonas Haskins has played baritone with Earth at various points. He's been involved in a few other projects, but I'm not sure if they're along the same lines.
