what are you making?
Swiss Emmenthal is sort of in the ballpark, get one from Switzerland, then read the ingredients to make sure the milk says unpasteurized milk. That will be closer to a Gruyere.
Costco often has both Gruyere (cave aged also, 2 types), and a half decent Swiss Emmenthal.
I don't know what you're making, but maybe a tiny bit of kirsch added if you have it, just to pop up the flavor a little more.