I had the Varmint stock, upgraded it to a GRS BiFrost with no regrets, and it might be worth considering. (OpticsW & Macleods' run periodic offers).
As has been pointed out, the only exception is the CTR version that has to accommodate a d/stack magazine, and the stock requires some inletting.
For most other s/stack magazines the outer diameters for the base plate remain the same, it's just the inner cutouts that change dependent on calibre.
Hope you manage to find what you're after.