2.76 vs 3.23 vs 3.55

With 3.55 you'll be turning 3300 rpm at 65 mph. As for fuel consumption. Can't say. Really depends on your setup. Depending on cam/engine that might be high or low to you. If you're spending that much time on the highway. And really concerned about fuel/power etc. I would sit down. Calculate each one. Drive at that rpm for an extended period (your average highway trip). See what kind of power you have. And see if the noise is too much for you. With your tiny tires and the 3.55, you'll definitely move off the line. Might become a problem in terms of grip depending on how wide your tire is.