Maybe a 25 caliber or 6.5mm? Or maybe a little bigger say 338, 358?

That's fine advice - really, provided you don't come on here and ask the question first.

I'd also add something on either the top or bottom end. .223 or .243 on the bottom, or something like a .338WM on the top. Nothing at all wrong with a good .30-06 though.

ah heck get a thumper, either a 358 win (my choice) or a 35 whelen. I sort of agree with bigger is better

I was thinking the same thing everyones gun safe needs aome sort of 30-06 like maybe in a browning bar.

The .45-70 is a fun old cartridge with a lot of nostalgia behind it. And still packs a whallop that is plenty for any NA game. Maybe in a Marlin 1895 Guide Gun or Browning 1885 single shot.
Or you can go the complete opposite end of the spectrum and get a .204 or .22 cal centerfire.

Realistically - you will use a smaller caliber gun far more than you will ever use a 30 or 40 cal.

Truth be known !!!

458 lott and go pin something to the ground. LOL