As the title says, is a 10 or 26 spline clutch recommended, or do I even have the choice?
Unless you swap your tranny input shaft for a 26 spline, you have to run a 10.
03/04 Cobra's use a 10 spline stock. I think even with the build in your sig, a 10 will be fine. You won't be dumping the clutch with a drag slick will you?