I don't understand your reasoning. All of this effort so you can shoot the longer berger bullets? Why not seat them to fit the existing magazine and SEE if they shoot. If you choose the hybrid lineup I am certain you can get them to shoot even if seated deeply in the case with a long jump to the rifling.
I have buried hybrids in the 300 WSM and 300 RUM with no ill effects. Both shot as accurately as other rifles. Can't even tell if there was a velocity loss.
Before you spend hundreds why not give a few of those long high BC berger hybrids a try, you might be pleasantly surprised.
Here is a pic of the 230 berger in the 300 WSM velocity of 2720 fps