Re: 7 mag build around the 168 Bergers?
If you are prepared to spend the money on a new barrel it might be a better option to get the smith to mill out the back of the action and fit an extended magazine box so that you can keep it as a STW and seat the bullets right out. It will probably be cheaper than a re-barrel too.
Otherwise try a 2 load system, say a 160 accubond seated to fit in the magazine, the ogive of the accubond will mean it will be closer to the lands, as the load for the close jump shot and then single feed the Berger for the long range shots.
If you are set on re-barreling then I use a 7mm mag with a 26" No 5 contour 1 in 9" twist. It works really well. But as you have a sendero there is nothing wrong with sticking with a sendero contour. I don't think you will need a muzzle break for a 7 mag, but it might help to spot your shots easier.
Wow, that got a bit long winded.
Hope it helps.