That's probably a good realistic goal for starting.
1st thing is get a good accurate rifle. Usually, a standard rifle that only shoots 1.5 inch groups at 100 yds is going to shoot at least 10 to 12 inch groups at 600 yds (by time you figure wind drift variances and other things) The vital zone on a deer or antelope really isn't alot bigger than that. Also, you need to figure in on some variables; like field shooting positions aren't usually going to give you the same consistency in shot placement as you would get from a bench or bipod.
You may not get consistent readings from your rangefinder(hint.......get one), the wind may be blowing really hard one shot, and hardly blowing the next, variable, variables, variables.....
In other words, the more accurate the rifle; the smaller your groups will be at 600 yds..........at least before the variables come into play. A gun that shoots 1/2" groups at 100 gives you alot more room for error at 600.
Good optics (not grandpa's 4X or 6X weaver) are also very important in my opinion. We can only shoot as good as we can see. Yes, I know some people shoot very good with iron sights, but it takes alot of practice. I think scopes in the 10 to 16 power range are great for shooting out to 600. Parallax adjustment is also quite important in my opinion.
Accurate Rifle and Ammo, Quality Optics, Range Finder...........that should get you started. After that, it's practice and learn, practice and learn, practice and learn.
Good luck and Thank You.