A real flavour bomb. Like negroni, the flavour combinations here are so extraordinary that it repays/survives many permutations. The punchy juniper of Botanist gin that I had came through well at 30mL; tempered by the Cocchi storico at 25ml, Green Chartreuse - still noticeably forward at 20ml, Campari 7.5 as written. Botanist gin created a palpable zing on the tongue. All up a brilliant flavour combination.
I didn't make the adjustments you did. But I made it twice with the Storico and St. George Botanivore. First time 2:1 Strega to green Chartreuse, then reversed the ratio second time. The Chartreuse character is essential. Strega is a nice supporting player if your Chartreuse levels are rationingly low.
Strega sounds like a very nice inclusion here - love a witches negroni! Have made this several times now and reverted to spec mostly. Plenty of dilution or even a good splash of vodka can help open it up.