About a year or so ago, when I started to reload for the 45-70 Marlin, Johnn Peterson on here, sent me an issue of Handloader Magazine featuring reloading for the Marlin 45-70.
I can assure you, you can load WAY beyond the figures mentioned by the OP. I have the 22 inch barrel Marlin with a Limb Saver, but no way am I going to load as high as the authors of the articles did with all three versions of the Marlin 45-70. It is the only rifle I ever loaded for where it isn't the pressure of the rifle chamber I worry about, it is my shoulder! Actually, the hard push of the recoil, rather than a sharp "blow," causes your head to fly forward, rather than hurt the shoulder.
Natesfitness, if you PM me your email address, I will scan a page or two from Reloaders Magazine for you and give you some of the loads I have used.