Decided on either the 7mm or .270
Sounds like you're buying this for hunting, not every weekend target shooting. If that's the case, the 7mm might be a better choice.
I will say the .270 is a fine cartridge and will still be great for Elk and the like. I just personally think the 7mm is better suited for an "all purpose" hunting rifle for North America. Either way, ammo is readily available and there are tons of reloading recipes for both calibers. Let us know what you decide to get.
Throat and barrel erosion will never be an issue unless you are shooting tons and tons of rounds over the life of the gun. And if you had that kind of time and money, re-barreling an action wouldn't be much concern as you'd have the resources to do it. In a true hunting rifle shot a few times a year, it's a non-issue.
Get yourself a Model 70 Super Grade in either caliber and you'll be happy.