An experiment with Clément Créole Shrubb:

The orange in the Shrubb is pretty strong.  It made the sides of my tongue a little numb.  Not altogether unpleasant…

2oz.                  Rittenhouse Rye
1oz.                  Clément Créole Shrubb
.25 (shy)        Fernet Branca (optional really)
heavy dash   Angostura Bitters