Same again, nothing really to add. A double with only one hammer cocked is a single-shot. No point to that...

I load 56gr AR2206H (=H4895) under the 350gr Hornady RNSP for around 1950 fps in the only .45-70 currently in my employ: a Baikal MR-221 double. That load pretty-much equals the British .450 nitro-for-black ballistics and is close to the modern Marlin lever-gun equivalent, so it could be 'hot' in a Kodiak.

I have always believed the Kodiaks were regulated for a heavier bullet at slower velocity, like the original Government load, but have never owned one. There have been discussions on these forums though, so using the 'search' tool should turn up plenty of good info.