Perfectly doable, not a gimmick, the 44 magnum in a rifle is a deadly combination to 100 yards. You obviously know the trajectory of your outfit, so no trouble whatsoever.
Most people don't realize how much more power the 44 mag has in a rifle, than in a revolver. It's like 250- 300 fps difference, and that is considerable.
Only thing I question is your suggested choice of bullet. I think the last thing you want is a hollow point in a 44 mag. Any bullet will make a big hole, you just want a bullet that will allow that hole to be as long as possible!
I would just use cast bullets in the 405-420 grain weight. A medium hard cast bullet will likely hold together much better than the typical jacketed soft point, such as those made by Speer, etal.
Wow, did I ever make a boo boo!I had 45-70 engraved on my mind, when it came to bullet weight!
With the 44 mag I would go with the standard 240 grain, but solid cast. The break up I mentioned does occurr with the 240 grain jackedt Speer, ets.