D; I know I'm going to catch it for this, but I would never give up a MK V for a Rem 700 to build a rifle in a Wby Mag caliber. Realistically, not handloading will make it harder to find the "magic bullet", but if you've tried all the available Wby and Rem ammo in your rifle, a custom build is an alternative. A Mk V with a #5 or 5.5 contour Shilen stainless barrel (no brake), in.300 Wby,in an Accurate Innovations stock will shoot sub moa groups with something, maybe with a factory load, but no guarantee on that. For $1200-$1300 out of pocket you will get a rifle that very possibly can shoot sub moa with some factory load, but absolutely can with the right handload.
In fairness, you can do the same thing on a Rem 700 action. The MK V is just my personal favorite.
I wouldn't be satisfied with 1 1/2" groups either.
Hope this helps, Tom
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time