re: ruger guide gun
Hmmm. Saw picture and specs. Large caliber in a poundage to resist some of the recoil. Muzzle brake to do the rest.
I do not recall that those particular chamberings are of calibers that can be found in a wide variety of places that sell rifle ammunition. IF I am correct, the price of one box of said calibers would be at a high cost, as compared to the cost of, say, .45-70 ammunition.
Yes, North American Guide Guns are more than likely to be lever action rifles, and in the larger chamberings, including .45-70 Government. There is not an animal on the North American continent, that would thumb its nose, when the .45-70 speaks. The only other two lever action chamberings, outside of some of these .45-based newer cartridges, are .444 Marlin and .405 Winchester, which Teddy Roosevelt used.
I would suggest looking on YouTube at a fellow named "Hickok45". he has a few videos where he is shooting .45-70's, and different lever actions, including guide guns.
I think you might have your answer, then.