Now you got me going here.... a moose hunt is on my bucket list for sure.... i would stay in the 12-20 yard range with a big critter like that personally.... if it's far enough where you have to think about yardage, it's too far.
The biggest mistake guys make on elk is looking at the whole animal instead of picking a small spot behind the shoulder to focus on. the tip of the shoulder blade usually throws a shadow line or a crease. try to focus on that crease, and wait till he steps forward and opens up the kill zone. if that leg is back you have no shot on an elk...a moose will be no different.
Here's a trick on judging distance....if they are still out of range or boarder line. look at their feet, or the ground right at their feet....Then pick a spot on the ground that is half the distance from the critter and double it.