What is the rpm sweet spot for highway driving

-what 273 said.
Personally I like 2200ish. Motor is just cleaned up, out of reversion. Shes feeling content.Almost happy. The vibration and noise are down. Its smooth sailing. Your engine with a smaller cam, could easily cruise at a lesser rpm. You aleady have the sweetest commonly available gear, the 2.76.
-If you need a bit more oomph, look to the engine tune, or a lower first gear. The 2.74 low set will get you 13% more grunt. Thats the difference between a 318 and a 360. But, its only good for first gear. Second gear falls to 6% increase. Thats the difference between the 318 and a 340.
-The only drawback is the larger splits.The rpms will fall more between shifts. Your cam should be very torquey, and get you through that ok. And if you find a loc-up, your revs will fall another 5% from your posted data-sheet. So its win,win for the trasmishin.lol