You'd have to sim it to be sure, flex totem + bindings and black blood + bindings at 50k iterations 600 seconds preferably. But I'm fairly certain that normal black blood > flex totem, the only real exception to the rule is bindings just kind of beats out anything. However once you get normal totem then you'll want to replace your black blood with that.
When you sim it, make sure you run a reforge plot, as the high amount of haste from black blood and the RPPM mechanics can cause significant shifts to the mastery/haste priority.