To tame that rifle body is simple...if you procure a butt that's full length and then put a recoil pad on that keeps it out there, plus a comb stock...that will take all the hurtiness away. The rifle comes up to align the sights and there's no room for rearward movement... A Parker-Hale type butt...
That is quite beautiful. That one in 45-70? What kind of 4570 loads can this Mk.4 action handle?