If you can afford the hunt, then you can afford a gun worthy of the game. While one can kill a moose with a .223 Remington, it's not what I'd choose.....IMO the old .30-06 is a minimum unless you can be assured that the shot you get will be the classic broadside shot to the rib cage.
If the only shot you get is a quartering away or toward you, then you'll wish you had a lot more gun with a bonded bullet for the penetration and energy level to do the job.