Can I substitute blood orange syrup for blood orange juice?
I can't get fresh or juice in my area.
How about blood orange beverage drink?
I think the beverage will be ok, the syrup will be sweet, so take that into consideration for the margarita. The syrup may not make such a good base for a drink, actually, but may work if you were using simple syrup as an ingredient in the drink.
Hopefully the beverage drink doesn't have much in the way of extra ingredients in it, just a % of blood orange juice with other juice. Beverage drinks are notorious for additives. Make one and see how it goes.