Take note of what
@smokey is saying in post#37.
I totally get needing to scratch the itch. Done it many times, with all sorts of calibres and cartridges. But I like precision shots with cartridges that have enough power for the target game, but not excessive amounts, and so I don't own a magnum any more.
A 7mm Rem Mag was designed for grizzly, moose, elk on Les Bowman's ranch in Wyoming. For shooting at long range. Not red deer and fallow at normal UK stalking ranges. A 7mm Rem Mag is way too much rifle for fallow.
A 7mm Rem Mag needs a 24" barrel minimum and a mid- to heavyweight stock. That makes for a lousy stalking rifle.
You'll forgive me for saying I think your mind is made up but it does risk being a white elephant, especially if most of your shooting is lowland woods.