You should contact Bob Mitchell at
13 Orchard Drive
RR # 1
Lindsay, ON
K9V 4R1
and ask him to send you his own manual on the 45-70. He probably knows more about the 45-70 than most people on the planet, including the "reloading manual writers". He gives an eye-opening account of his own personal research on the full potential of the 45-70 handloaded round for three guns in particular: the Ruger #1, the 1895 Marlin, and the NEF Handi-Rifle 45-70 single shot.
I just finished my first read of his 45-70 manual (he has written on other calibres too) and am about to read it again. I won't be going back to my "store bought" manuals for my 45-70 Guide Gun when I decide on a load from Mitchell's book. It's well worth the $20 he asks for it.