First ammo availability seems to be a big driver here, so the choice really boils down to what the OP can get.
So, go with 270 or 30-06, you have your good ammo selection and get a butt pad if needed so you don't get a flinch (I like the butt slip on type but others prefer strap on or you can go permanent limb save type)
Second recoil is truly subjective. I shoot 1917s bare metal against a T shirt in the summer and am fine with 30 or 40 of those. My bother with a jacket on thought it was worse than my dada 1903 very light Sporter. go figure.
A recoil pad works wonders for practice (which I do use on my dad light 1903 and the even heavier Sporter A3 I have if I shoot it with a T shirt). I tend to shoot 60 or 100 rounds at a session though as mine is target shooting these days.
As for Bart B, he is right, Performance wise the 300 magnum is better than a 30-06 but can you really USE it and do you really NEED it?
My point though is that with a powder like R17 you can (and Hornady makes factory ammo ) that matches the old 300 WM performance.
300 WM of course can use the same to increase its reach. But you PAY for that reach as its velocity issue (if you can do the same velocity in a 30-06 with the same bullet it would be the same). Personally I find the necked down parent cartridge like the 7mm Rem mag and the 300 mag nasty beasts.
But if a 30-06 in the old says took everything on this continent as well as Africa with its less stellar ammo (before 300 mag was available in 1963) and you get better 30-06 or 270 performance now, how finely have we sliced things so a 300 mag offers anything most of us can use? It may sell guns but sales apeal vs what we need and works is a different story and I encourage people to look at that and assess what is really needed vs the bigger bank thing is better. Good shooting and right ammo wins every time. A 300 mag is not going to make me a better shot.
Lot more boom and powder and probably only someone like Bart B could take advantage of any range or trajectory improvement.
300 yds is pushing it range wise for most of us, 400 is certainly so. I missed my one 450 yd shot (I cut the skin on top but the cigar was a lucky leg shot by my brother). I saw my brother make a paced 450 yd shot, clear field and he was able to drop on a hummack and do it prone not too often and he is a darned good field shooter.
Paul, please explain how the 7x57 can be reloaded to equal or surpass the .280 for a given bullet with equal peak pressure and barrel length when the .280's case has near 25% more volume.
That's about the same claim based on the .30-06 matching or bettering a .300 Win Mag.