It is not uncommon to see Bijou recipes with equal parts gin, Chartreuse and sweet vermouth, as called for in Harry Johnson's Bartender's Manual. In fact...
Love this drink! Used Beefeaters to try an old classic London Dry and used my Genepy sub. Which I’ve grown fond of..and Carpano. Did not see bitters until later. I’ll try that next. I have now Green Chartreuse but save it for special occasions now!