Agree with Chris that this on the sweet side. Due to kinas being unavailable in Australia, I went with 22.5ml Cocchi Americano. However, it was lacking in bitterness so added a little dash of orange bitters. Vintage, no punches pulled flavour. Would likewise be tempted to up the gin a tad to dry it out and add more definition.
I cannot get Tempus Fugit Kina L'Aero d'Or in my home state, either. I found a bottle by accident while buying wine on vacation at a wine shop in Walla Walla, Washington, a thousand miles from my home. You might try Bonal Gentiane-Quina Aperitif or Luxardo Bitter Bianco, both of which I like better than Cocchi Americano for this sort of recipe. And the recipe only has 2 oz of liquid in it as is, making it easy to add a bit more gin to dry it out. The 6:2:2:1 proportions work well, IMHO.
Walla Walla. Interesting vacation destination. Welcome to the Inland Empire! I know of a mountain ridge in north Idaho where you can see all of eastern washington to the Cascades.
Got hold some Bonal and, yes, it really added herbal depth and bitterness to balance the sugars and richness of the Lillet and apricot brandy. Good stuff!