I never understood whyu Alfa made !st different. It had to cost more to make the two unique pieces than to use the ones on all the other gears. I know this started back in the 50's with the Gulietta 4-speeds, but really.
In addition to the 1st gear sector, the 1st gear is really heavy. Lightened gears are great for a slick shifting transmission, though they are hard to do because they are so hard. Induction hardening is fairly deep, and it takes carbide tools to cut or drill. You can save a few bucks by just milling the first gear, which has the greatest syncro load.