I would probably recommend a 5.5-22. I know others have recommended 8-32. Personally I think 8X is a little high for low end if you don’t have plenty time to observe your animal and get setup for the shot.
Magnification is a question you will have to answer for your self. I think if this thread were on the smokeless muzzleloader topic you get more individuals to respond. A friend is running an SHV on his break action and my brother runs an NXS on his bolt gun. Until 2 years ago I was a Burris guy my brother and the other friend were a Leupold fans. That all changed after shooting Nightforce optics.
I’m planning on ordering a 6x24 Sightron 111 with zero stop. For hunting purposes out to 400 yards . 5.5 or 6x out of a 50mm objective doesn’t seem to present a problem for closer shots. Acquiring close range targets with both eyes open helps.