I think the two considerations I would throw out for your thought have already been addressed, but just for the heck of it...
1. Over-penetration. Generally I think this is over-rated but a .45-70 would get me thinking about that. In your case, sounds like it's not an issue.
2. Recoil for efficient and effective follow-up shots. If you're comfortable with it, not an issue.
I guess a third would be weapons familiarity. You need to be as comfortable and familiar with a SD firearm as you are with your skin. If you spend a lot of time with the .45-70, that would be a plus for its use in your case.
1. Over-penetration. Generally I think this is over-rated but a .45-70 would get me thinking about that. In your case, sounds like it's not an issue.
2. Recoil for efficient and effective follow-up shots. If you're comfortable with it, not an issue.
I guess a third would be weapons familiarity. You need to be as comfortable and familiar with a SD firearm as you are with your skin. If you spend a lot of time with the .45-70, that would be a plus for its use in your case.