I played around a bit with some of my whistles today and noticed that the outer diameter of the tube in the Walton’s Little Black Whistle and the Nickel Generation D were the same. When I tried swapping the heads I found out that the combination of the Nickel Gen D tube and the Walton’s head is very sweet. The tone is much more stable than with the Gen head and the octaves are much better balanced too. The characteristics of the Little Black D didn’t change as much with the exception of the bell note which is a bit out of tune…
I’ve definitely got a new favorite whistle! 
Cheers,
Anders