Carsiding and drywall

I will soon be putting up carsiding for my ceiling in the attic remodel. The ceiling is vaulted. For the knee walls, I am using drywall. My question is, does anyone have any idea or experience with how to properly make the two materials meet. I don't want a huge gap at the top of my knee wall (start of the ceiling). I know on a stratight wall chair rail works, but since the ceiling is slanted should I use?

 

For a "huge" gap I would use a 3" crown mould. Or, you could rip a piece of 1" x 4" to fit the angle precisely.
Glenn