OK, bass trombones. Here's a little something I cooked up on the fly the other day. It's nothing fancy but may be useful.
It is the famous Rheingold excerpt played using an organ setting in general midi. The tempo is quarter note - 60.
Yeah, I know it uses equal temperament but you may find that french horn section isn't planning on just intonation. If you can lock in with this, it's a good start at any rate..
Here's the mp3 file.
If you want to tweak it, here's the midi file.