The 265/70's would make you about 2.5% under geared instead of the 5% you will be w/your current tires and the 4.10's, either way the performance/mpg's should be better than the 10.5% you are under geared now.
If you decide to stick with the 265/75's, the 4.30's would be about stock performance, for better than stock performance the 4.56's would be my choice. 4.56's would be about 5% over geared, which would liven up the light-to-light performance w/o sacrificing hwy mpg's as they would only raise your rpm's by 120 at 70.
Before you consider intake or exhaust upgrades, I would toss a 4.56 geared 3rd in and see what performance is like, the 4.56 gear set was a factory 3rd and you can usually find them used for $250 or less.
