I'm building a 338 RUM which is similar.
I'm using CIP length magazines (300 RUM from Accurate Mag) but some actions and stocks can take longer magazines and blind magazine boxes which helps when you are loading heavy and long bullets.
Since I'm constrained by my magazine, I went with the 0.090" shorter RUM instead of the Edge.
I'm maximizing my barrel length to try and get back some of the velocity I'll lose so the difference will be pretty minor unless you compare it to a +P chamber.
Lothar Walther is cutting my barrel as a prefit and I'm putting it on an American Rifle Company Archimedes long action and their Xylo chassis. All I have to do it wait for the barrel, torque it on, load up some ammo and then I'm ready to shoot.
There are many things you could do differently that would require significant gunsmithing and in that case, Defensive Edge seems like the place to go since he developed the 338 Edge.
In my case, I determined that 338 RUM was probably the best ELR cartridge I could build up with pretty much standard (a bit high-end) off the shelf parts.