My current reference for .45-70 is a single-shot Pedersoli 1885, but I owned a Marlin 1895 previously, too. Starting 'lever-action' loads with IMR3031, 4895, and 4064 and a 350grn bullet were punishing. So much so, that I actually pulled over 100 cartridges rather than just shoot them up... I would rather have a root canal without anesthesia over pulling bullets. Just saying. I really think, based on my experience shooting cast bullets at steel over distance, that a powder in the IMR4198 range is the way to go. That is not to say Unique, TrailBoss, and 2400 aren't avenues as well, or reduced charges with something like IMR3031 or H4895 (Hodgdon provides reduced loads with H4895 specifically...) Just my .02 worth.
BTW, you have yourself quite a rifle there. Good job!