I would find a light wadcutter, say 110 grains. Load it as hot as she can take, recoil wise. Full house loads with HS-6 will give you between 1100-1200 fps.
There are two ways to get a large wound channel. One is an expanding bullet.
The other is using a cast bullet, but pushing it fast, between 1100-1350 fps.
This would give you a longer, bigger wound channel then an expanding bullet, because the expanding bullet would not penetrate well, and, the velocity creates a larger wound channel, combined with the flat, large nose on such a bullet.
In addition, the bullet might tumble, adding wounding as it goes through.