So I picked up an MGW shifter for the Shelby. I've never used MGW before, but from what I've read it's received great reviews, and appears to be a great piece. I also went for the black shifter knob with cobra logo, along with the adapter shaft so I can also swap to the stock knob later.
Ford's supposedly coming out with a "fix" for the 1-2 shift grind on the GT500 sometime in May, so I'm going to wait to install until I hear exactly what that fix is going to be.