There was an interesting article in "Big Bore Rifles & Cartridges" written by Bob Hagel on the .338-74 Keith years ago and the rifle was a Ruger No.1, too.
Always peaked my interest; too many other rifle projects and not enough time ..... sadly.
I had a good friend who owned one. He was a friend of Elmer Keith and used loads that were recommended by Elmer. It was built on a #1 Ruger with a barrel by Iver Henriksen. He told me it shot very well and accounted for many elk and mule deer. Sadly, he passed away a few years ago and I never had a chance to shoot it.