80 or 90 grains will put the whammy on the deer with those big slugs, believe me.
I have killed lots of deer with 80 grains of black powder, and the .490 round ball. It is only 174 grains.
With the bigger bullet, and the same powder charge, you get more foot pounds of energy. A lot more.
Most of those shots I made with a TC Hawken, same twist as your Renegade.
I might suggest that you try patched round balls, they are cheaper than those big slugs and are just murder on deer at 75 yards or less.
Maybe, when you run out of the big slugs you could try a box of patched round ball.