Mike,
For many years people have been able to use Rem 700 mounts on a Mark V. Was this the perfect match. No. the dimensions of a Mark V and Rem 700 are different and today are even more different then years past.
Weatherby has not changed the Dimensions on the Mark V for many many years, so all of our Talley mounts will fit most any US Production Mark V. If you have specific questions about a rifle you can always call and ask for Technical Services.