As you may have already noticed, several of us recently took on the 445 Super Mag as a project just a few months ago. As a part of that group, and someone who has taken game with it already, I'd say you are on the right track.
Those of us using 22" barrels and 30gr. bullets are getting just under 2000fps now. With 265gr. bullets we are getting right at 2050fps.
For the application you have described, and going on the data JHP45 came up with in velocity vs. bullet weight in a 1:38 twist barrel, I'd stick with the 265gr. bullets.
I amd SERIOUSLY considering an attempt at an Elk with this cartridge and a 265gr. Beartooth WFN bullet. If I can get a shot under 200 yards, it will be done.