What Gun to Get?
Most firearms from major manufacturers function as designed and shoot well. The most accurate model is not always the best. A gun that shoots a two inch group at 100 yards with a good bullet will drop anything on this continent a long way farther than 99% of us should be shooting at.
Rifle Scope and Mount for Big Game Hunting
A quality riflescope of late manufacture. Any quality scope will be fully multicoated, waterproof, fogproof, shockproof. A scope with a magnification range of around 3-9 power will work for almost every big game application in the world. Expect to pay about as much for the scope as the gun. Low power is more important that high power in most cases. Mounts are equally as important to secure your precision equipment together, and prevent movement under harsh conditions.
Get a Gun Case
Especially if you're flying, a hard, lockable gun case sturdy enough to prevent damage by heavy equipment, and secure enough to prevent a fairly determined theft. Waterproof. Wheels and handles. Get it at least a size larger than what you think you need. Get one with a lifetime warranty and you will have it for a lifetime. Bring a gun sleeve, also, so you don't always have to bring your big case, if not necessary.
Binoculars for Your Big Game Hunt
Consider bringing two. A medium sized binocular, and a pocket sized. A quality binocular is as important as any gear you'll have, since that's what will help you spot your game most of the time. The more you look through your binocular, the more the quality of it matters. Eyestrain can result in a headache that can screw up a hunt, especially in many hunts, where most of the day is spent glassing. Every day.
Get a Flashlight for the Hunt
Several flashlights are not too many. I keep one in my gun case. One in my backpack. One or more on my person. One in my emergency gear. And lots of extra batteries. Lithium batteries weigh half as much and last twice as long. A good headlamp is so important to me that I bring a spare. Have at least one modern light with enough power and longevity to trail game, and illuminate the animal when gutting and/or quartering. Red lenses save night vision. Green is easier to hide from game.
A rangefinder will generally NOT read a game animal at anywhere near its maximum rated distance. Those distances are rated for a large, reflective surface during ideal conditions. A deer can be read at roughly 2/3 the max distance, or less. Most come with amazing bells and whistle technology. If you are the type that uses all the features on your smart phone, you may be the rare one to use all the features in a rangefinder. All that's really needed, though, almost all the time, is to press button and get a distance. It's up to you to know the trajectory of your bullet.
What Backpack Do You Need?
Get a backpack with enough room for your requirements. In cold weather, you may need to remove a layer or two. Clothing takes up a lot of room. May you have to stay overnight? You'll need a lot more room for gear. Do you have to pack out your meat? If you do, cover it somehow first, so you don't mess your whole bag and all your gear. A waist strap is required. It removes and redistributes weight and is much more comfortable, besides making your pack more efficient.
Practice for the Big Game Hunt
There is no substitute for trigger time. Experience cannot be bought. Shoot the gun. A lot. With the clothes you'll wear hunting. Off your bipod or shooting sticks. Kneeling. Standing. Run to your target and back a couple times and then try to shoot while your heart is bursting and oxygen is nonexistent. Wear your hunting boots and gloves while doing it. With your pack on. Practice how you will hunt, and try to weed out any potential issues before they become fact. Use plenty of fresh targets.