I made this with Laphroaig 10 & Gosling's. It really brings out the "iodine" note of the Laphroaig, so I'm not sure that's the best option for this one...
A found a 1:2.5 ratio prevented the ginger beer from getting overpowered, but I imagine it depends on the whisky and beer you're using. A dash of bitters is also welcome