Those slugs have a .162 sectional density, which is abysmal.
Even the 147gr 9mm is higher at .169.
May work, but if you want far far far better odds, buy something in the Africa Dangerous Game calibers, like 375 H&H and use that, you can run .300+ sectional densities with massive stopping power.
They aren't a little better, they are far and away better, not only that, a 375 would likely have more enjoyable recoil than a 3.5" 12ga slug.
12 gauge using tungsten super shot in an appropriate size would be interesting given its penetration, it'd still be a 3rd gun scenario as far as I'm concerned.
Good luck and I hope the shotgun and slug works, but boy are there better options, especially for the recoil.