Forget 750 yards with a .270? Why? 28 and 26 calibers on the same size case behind the neck have done very well at that range. With match bullets, the .270 will shoot 3/4 MOA with only half decent ammo in good rifles.
The (.270)cartridge is not up to it? Well, their bullets in Sierra's test range shot in the 1/4 to 3/8 MOA sized groups at 100 yards.
A (270) 140 grain bullet, for example, drops 97"(8 feet) at 700 and that's not an issue at all as long as it drops the same amount for each shot. Accuracy is not measured by how much a bullet drops at any range.
Regarding stock screw torque......
Win. 70's shot best in competition with all three screws at 60 in/lb with all barrel weights, cartridge as well as barrel length. Those using Rem 7XX based rifles performed well with 40 to 45 in/lb on front and back screws, 25 to 30 on the middle one.