[Wilko]

To be honest, i wouldn't change much about it. The number you get is fine, the damage is ample without being too much, and mustard gas is mustard gas, so the color probably wouldn't vary noticably from Army to army. The only thing i could fault would be the skin on the cannister (for the British/Americans, at least), still says 'Smoke' on it. you might consider amending that skin.

Other than that, i seriously wouldn't fiddle with it that much.