2.76 vs 2.94 gearing

Now this is my opinion.
3.21/3.23 are what I consider great balance gears, decent off the line with some highway ability.
2.76/2.93 are great freeway gears, but it will leave off some pep off the line, and as you've stated here would be good since you're just cruisin' and do a lot of freeway drivin'
Some would even consider 3.55 as great balanced gears, to some extend it is (again IMO) but at 70+ mph it'll be a bit buzzy.

I have a pretty hot 360 and I have 3.21 gears (8.25 axle). And I've done a few 500+ mile trips with it.
With 26 inch diameter tires at 3000 rpm's I go about 71-72 mph, The absolute best was a little over 17 mpg. Mostly hung between 15-16 mpg.
Now I can imagine what would happen if I had 2.76 (about a 15% reduction in RPM) going the same speed but only doing about 2500 rpm...

That being said I have a 3.55 8.75 axle I'm going to be putting in soon *sigh* I guess I am a glutton for punishment... But maybe it'll motivate me to start my OD project sooner.