Whisky has become the standardized spelling in Scotland, but formerly both were acceptable, if you read the old literature and broadsides. Forgetting the Gaelic which is not verified earlier in print, the first printed usage in Scotland of the word was whiskie (1715). The plural is still whiskies. Modern trade usage is whisky. Say single malt and avoid confusion and blends.
This is a little like the rope-line argument of the chantey singers.

The McCalmans version- do they include "Macallan" in the verses?
Also no mention of the robust Laphroaig, or the smooth Highland Park, etc. How can one sing the song and omit any of them!