Hi Darren,
Congratulations on getting drawn!
Here's a call that has worked well for me on five moose hunts.
http://www.buckexpert.com/languages/...Elowres2k9.pdf
It's one of their reeded mouthpiece/detachable plastic cone models. The accompanying instructional CD was a big help. Well, that and a pile of practicing

.
I'm guessing here but I think in Maine more moose have been dropped by 30-06 cal than anything else. I use a 7mm Rem mag with 180gr bullet.
Obviously, the habitat you'll be hunting in is another determining factor in your gun selection process. Will there be some large clearcuts or agricultural fields like we have in northern Maine, or will you be in the tight woods? The average shot distance on the hunts I've participated in has been 50 yards, although during scouting a lot of moose were seen up to 300 yds away.
Here's the State of Maine's take on gun selection :
(From Maine Fish and Game Moose Hunter's Guide)
http://www.maine.gov/ifw/licenses_pe...ide_FINAL2.pdf
(Good reading, regardless of which State you're hunting in.)
quote: "Making The Kill:
You should make every effort to kill your moose instantly. This requires use of the proper firearm and the ability to hit vital areas. To have greatest assurance of making a clean kill, only the larger cartridges are recommended.
NOT Recommended
.243 or .244 (6mm)
.303 Savage
.38-40 Win.
.250 (.250/.3000)
.30-30 Win.
.32 Win. Spec.
.38-55 Win.
.35 Rem.
.25-06
.32 Rem.
.44 Mag.
.351 Win.
.257 Roberts
.32-40 Win.
.44-40 Win.
.30 Rem.
Recommended
.270 Win.
.30-06 Sprfld.
.308 Win.
.284 Win.
.444 Marlin
.280 Rem.
.30-40 Krag.
.348 Win.
.303 British
.8mm Mauser
7 x 57 mm.
.300 Sav.
.358 Win "