My 300 H&H comes pretty close to what you're planning, it's a pre 64 M70 action, Lilja #2 @24" Echols legend stock, factory BM and with a swaro Z3 3-10x42 on top in comes in at 7 3/4 lbs, shoots and handles wonderful.
Yep, excellent choice there. I also have a semi custom pre 64 built on the H&H receiver, that is now a 338WM. The thing is 8 pounds all up and drives tacks. When I had the Swaro 3-9x36, it was 7 3/4 pounds. That's right around the weight the OP is looking for. A light barrel and stock make a lot of difference when it comes to lightening a model 70. Forgot to mention my 338 wears a Brown PoundR, which is very light and rigid. The ergo's of the stock really help to mitigate the recoil of the magnums. One warning I have about using a hunter's compact edge. They really don't help to soak up magnum recoil... A stock's comb that is more parallel to the axis of the bore, and with less drop, usually mitigates recoil better. Kimber has a really well designed stock, very similar to the brown poundR, I use on my 338..:
You could always try a Bansner on a model 70 as well, they have similar ergo's as the kimber montana stock:
As for just going out and buying a Kimber montana, well you takes your chances there.. However, some guys here have been pretty good at rolling the dice lately...