Can't omit the Ango, but don't be too heavy with it. This recipe most suited me: 45 ml sherry, 30 ml Dewar's, 20 ml pineapple syrup, 7.5 ml lemon juice... Same overall volume, just shifted. You got a better idea?
Not bad but being Angostura Bitter's Birthday, I'm surprised you didn't choose a Trinidad Sour as the cocktail of the day for such occasion ( 1.5 oz/45 mls vs 1 dash of Angostura) ;)