I'll step up and take some heat... I shoot a .300 Win Mag and I agree with most of the remarks here about getting close. It's probably better to do that but... I don't know you. I don't know how you shoot, but the 12" at 950 is a beginning in my mind. At a longer distance, you should have more time to evaluate the shot. I suspect if things are right and the moose isn't in a herd that was spooked and are in a jog mode to get away from whatever was the cause, and they are just grazing and walking then stopping you should be able to range it, take your time dialing in the scope and placing the shot EXACTLY where it should go. If you have the optics to do the job, a great rest, and the conditions are good... I'd go for a decent shot placement out to about 500-600 yards with a 200 gr SMK or GK bullet. I'd prefer the 208 A-Max at about 3000'/sec but that's just me.
The ballastics on a 200 gr SMK @ 2900'/sec are included for a 40 degree F day at both 1000' and 5000' elevations.
As you will see if you look, the drop at 600 yds is about 70" (5.8') at it still has about 2000'/sec velocity and 1750 lbs of energy... which I would think is sufficient to drop your bull moose if you're as good a shot on a live target as the steel disk at 950 yds. As has already been stated, closer is better but you don't always have that luxury so if you're confident and can range the target, know the angle if any, can throw together some quick ballastic calcs in your head, I'd be fine with a 600 yard shot but out to the 950 yard mark the energy drops off so much that you'd need a really good upper neck/head placement to be marginally effective. (If you could move up to the .338 Lapua... now that would be a different story... and chapter to this novel.)
PS: You need to develop your own handloads and chronograph them to get a good ballastic chart to cut and paste on your stock for your rifle. Go with a good heavy bullet with great B.C. numbers, the gameking sierras' are fine or the Hornady A-Max versions or the TFX (I think it's called) are all knock down bullets... keep the velocity up and the weight up for accuracy, not just speed. Work it out to the 700 yard range and make that your limit. Hit the 12" disk 12 for 12 at 700 and you're ready. Have a fun trip and be sure to post pics...