does the Gamma come in different widths -...
does the Gamma come in different widths - need 143
This saddle is 142mm wide so it should fit just fine.
Also, when I was looking for Fizik saddles I used there spine concent tool. Even though it is a little cheesy with the "Find the animal within you" tagline, it will put you on the best saddle for your body type.
You'll be fine on the Gamma if you're looking for a 143mm width saddle