Having butchered and field dressed more than a couple animals, here is my .02 Velocity causes the most meat damage. Period. I for one, use bloodshot (or blood splattered) meat for dog food.
Using a .270 V 30-06 example. Both on deer, both with premium bullets, the 270 wasted more meat than the 30-06. And 7mmMag was the worst of the bunch for wasted meat (all shots were H/L)
Edit: Saw an underarm shot on a decent sized deer taken at 100Yds last year with a 300WM. I wish I could show the pictures, but essentially the complete shoulder was unfit for anything but dog food. So out of a possible 110lbs of meat, the winmag wasted 27lbs FYI
So 300WM or 45/70? Either works. If you plan to eat it, based on ONLY those 2 caliber choices, I would give the 45/70 the nod. If not, I would go for the 300WM
For a decent all around caliber 30-06 is darn hard to beat. And my go to choice when hunting. When on bear watch for other hunters, My 44 Mag lever action carbine, 12 gauge is my 2nd choice.. I take nothing for granted when hunting.