Vance, it's the old Ford vs Chevy argument we always get into & everyone gets a bloody nose once in a while, then we shake hands & have a good laugh....who won?
In your case because of the big bears, use the very best bullet you can buy because it might come down to one bullet. The really good bonded jacketed or flat nose solids have never been better & velocity doesn't phase them.
Good cast bullets will always have their place but you have to understand 2 things with cast, speed & hardness. If they match you are fine, get either one out of it's comfort zone & it's easy to fail.
Of course all of the above depends on bullet placement, we all agree on that, but if they are the same & we're hunting in Alaska where big starts at 6-700 lbs & can easily go twice that then you have to rethink your bullet selection.
Your moose sounds like he was one tough son of a gun, that happens even with that big hammer you were hitting him with.
I shot my Idaho bull with a Ruger SRH 480 & a 370 gr cast bullet at about 1050 fps through both lungs, one shot & about 6-7 seconds & he plowed into the snow. Maybe if I had shot the other bull standing next to him it would have been an out come just like what you had. That's why hunting is never the same.
One difference, my cast bullet was a softnose cast, but went clear through both lungs at about 45 yds offhand.

Dick