Congrats!!!! That thing is a MONSTER!!! Sounds like a story you'll remember for a lifetime.
I've hunted deer and elk in the Rockies as long as I can remember. Heck I was concieved on a deer hunt but let's not get off topic. I've always wondered how run and gun hunting/shooting in the high country compared to military shooting. It sounds like they can be two different animals in some cases. I spend a lot of time and energy practicing for scenarios exactly as you found yourself in. I've even passed up some shots because I couldn't get steady enough.
You probably have forgotten more about shooting than I know. With that being said I have always believed that proper breathing was important to accuracy but when I'm out of breath I have found that if you can aquire your target quickly it's helpful to hold your breath and you will actually be a bit steadier. Works for me anyway. I only hold my breath though when I'm panting heavily......it's not something I would do in a calmer situation. Has anyone else tried this?
Moose calling can get confusing to some, but cow calling is your main tool when moose hunting. If you go out and buy moose calls I would say you're wasting your money unless it is the birch bark cone. I find most store bought moose calls sounding worse than puffing a grunt your hands to make the call. You can roll up a piece of birch bark in a cone shape to use as a call and spend your money on a video that teaches you the basics of a cow call. A milk jug or a coffee can with a hole and a rope...