Daryl,
I just found your reply and question. Sorry for the delay.

You stated "Those are the ballistics of the 300gr. .45/70 trapdoor factory load now."
Not in the current Lyman load book. There it is the velocity for 1886 Win and Marlin 1895.
What I shot those white tailed deer with was factory Winchester ammo advertised to be at a MV of 1850 fps.

No, the 300 grain Nosler PP used in Africa was hand loaded to 2200 fps.
Our pre trip experiments showed that 2200 fps was the impact velocity that caused the bullet to explode, so we loaded to that MV. Since that Leopard was shot from only 20 yards, the impact velocity was not much less than 2200 fps.

This discussion does show that the 45-70 is easily up to shooting and killing African Leopard.