Made this with the called for Meletti and feel that it works best here, particularly with the chocolate bitters. All of the substitutions with similarly less bitter amari add citrus elements whereas Meletti's caramel and saffron notes do not. Worth having a bottle of it in your bar if it's available locally in your area if for nothing else than making a proper Sharpie Mustache and specs like this one!
Delicious depth of flavour (we used Amaro Lucano), although we were surprised by the 9 rating on the Strength/taste scale: we thought it a relatively mellow drink.
No Amaro Meletti or Silvio so I, too, used Montenegro. Not your standard rye cocktail; Clapham comes through again. The chocolate bitters (I used Angostura) are quite good in this, tying together the unconventional combination of ingredients.