i would go with a heavier contour barrel, less recoil and better accuracy, on average.
the swede is fine with a 1:9 twist, that's what mine uses, and i get good groups from both 100 hp's and up through 130's. i have not tried 140's but the 120's will damn near equal a .270 with a 130 grain bullet if you load it right.
have the barrel throated normally, like any modern rifle. sometimes smiths will cut them like the old swede military guns and you will have a heck of a time getting results with lighter bullets.
if you want to shoot a load the kids can handle, i use 42.5 grains of Varget with a 100 grain Nosler BT. Shoots way under an inch, and is travelling about 3200 fps.
i also recommend IT&D Gunsmithing in Medina, Ohio. great work and i got my mauser barreled with a featherweight contour douglas xx air gauged barrel, stainless, about $300 total. very good price.
-Matt