Re: .308 norma mag
If you are infact wanting the .308 Norma Magnum then you would be using the Remington 700 LA (same bolt face as .300 WM, 7mm RM ect ect) I never said there was anything WRONG with the .308 NM but it is often times confused with the .300 NM and .338 NM which are entirely seperate chamberings/brass ect.
So yes, a good smith COULD stick a Remmy LA in an AX chassis and chamber it for .308 Norma (just guessing here) I dont see anything that would be preventing the firearm from being functional, just different then most.
The .300 Win Mag would allow you to get an extra 100 fps on the .308 Norma Mag (given same wieght projo) and have a much wider selection of dies, brass and already loaded ammo in a pinch, but if your set on the 308 Norma Mag... So be it!