Both the Last Word's name and the simplicity of its traditionally equal parts recipe lend themselves to adaptation. It is also very much a bartenders'...
I believe the cocktail you are looking for with Quince gin is the Last Drop. It was uploaded by a fellow Discerning Drinker, Giorgi Aleksishvili so you need to be logged in to be able to view it. I found it by going to our Cocktail Finder and, under By Base Spirit, selecting “Gin – Quince gin”. If you are logged in this search reveals two cocktails, one being the Last Drop.