Pick Unit 71 and shoot something with horns on it unless you have a controlled hunt permit for 70.
Hopefully you have someone to show you around. 71 is big country. If 70 wear lots of orange and watch out for the crazies....... Also be aware of the Rez boundaries. The Indian don't like you shooting their deer.
Prepare for a long shot but expect the short shot.
Distances will appear very different than what you are used to. A range finder would be handy for general familiarity. Don't rely on ranging reticles.
I seem to remember from somewhere that 1000 feet in elevation is good for about 0.10 MOA. Those units aren't very high. Do the google earth thing to get an idea.
Don't change the way you sight your rifle just because you're headed west. Stick to what you're used to.
Other than that have a great hunt and sneak over to Blackfoot and eat lunch @ Rupe's. Best burgers in west of the Miss.