Both seven and thirty will get you to a mile
You run out of usualble weight class with 7mm at 180/190 grain which can be marginal to stabilise (190 grain that is) and 230 g with 30 cal
A big trade off with the 30 is recoil especially with 230’s
I’ve built numerous F class rifles in both which whilst the max competition range is 1200 yd if you don’t tell the bullets, both will happily travel to beyond a mile And remain supersonic, stable and accurate
My preference for a longer range rifle cartridge would be a 7/ 300wsm or straight 300 wsm
Without going into larger calibres and higher budget (read 338, 375, 408 class cartridges ) you will find a compromise with 7/30 cal
You also need to factor in a suitable scope mount with adjustable incline or high fixed incline and a suitably large adjustment scope with repeat accurate tracking
Load development
Shooting abolity
Wind reading ability
Stable rest
Accurate base rifle
All other factors to take into account to a facet of shooting that can be a real money pit and high grain factor at the same time