Generally, 2 inches high @ 100 yards gets most people with most deer rifles a decent point blank range. With the 30-30 it gets you somewhere past 150 yards.
My advice is to download PointBlank software (it's free) from the web and crank some numbers. Things like Ballistic Coefficient, muzzle velocity, etc can be found on the ammo mfg's website. You can guess and fudge a little here and there, but the important thing is that you get a good representation of how the bullet flies below, then above and back below the line of sight as it travels.