While the proportions of the classic Negroni are accepted as being equal parts, with some boozehounds slightly upping the gin, the proportions of this...
Can I suggest putting the gin first in the ingredients list? That way it's clearer that this is a negroni variation. Sure, it's right there in the name of the cocktail and the description, but the "spirit-liqueur-vermouth" trinity is such a convention it seems worth it. It would also match other similar variations such as Cin-Cyn.