Not on a Bronco, but I had a '66 GTO with a 389 and tri-power. It depends on what carbs you're thinking about running and how heavy your right foot is.

The GTO tri-power setup was very simple and, if you kept your right foot out of it, got very good mileage for that car and engine. It ran off the middle carb most of the time, so that carb had all the typical adjustments. The end carbs had almost no adjustments, so tuning was easy. The linkage was progressive, so that the end carbs were usually shut all the way. Once you stepped hard enough on it, the two carbs would pretty much go from shut to wide open. The acceleration when you did that was awesome,

but then you could actually watch the gas gauge go down. ;D