I’m going to provide you with my biased opinion on a Winchester m70. It looks like you have some great classics calibers already. I purchased my latest Portugal made Winchester featherweight in 270. A time tested round that is still keeping up with current trends in ammo choices.
Round capacity would decrease from 5 rounds of 270 or 280 down to 3 when using the 6.5 prc or 6.8 western rounds. Ammo is ridiculously affordable compared to 6.5 prc or any other mentioned caliber (I find boxes of 270 on sale do $20/box at times) which is great for practicing/trigger time. I have had great luck with accuracy being sub 1 moa for me. I’m not a target shooter or reloaded so it is as accurate as my tikka that I customized (6.5 proof carbon barrel and Rostock).
Recoil is the lightest with a 270 out of all the calibration you mentioned. You could always rebarrel to the 280 if you change your mind about it later on as well. The other two calibers you mentioned are both magnum bolts faces which you already have in the 300wm.
One caliber to possibly consider that Winchester offer their rifles in is 25-06. For deer and antelope it would work great.
Realistically as others have mentioned, the ballistics are relatively close to each other in sub 500 yard hunting ranges. My last few hunts the animals (antelope, elk, mulie, mulie) have been taken at 105, 80, 70 and 45 yards respectively here in Nevada. I grew up in the Adirondack Mountains in NY and hunting there where sneaking in on deer was how you hunted. My longest shot taken in NV was at 650 yards on a mule deer with a 300wm 190g Barnes lrx.
