Do yourself a favor, try putting a 45-90 cartridge, at least, in the ramp of your 45-70 to see if it fits, I have a 45-90 Pedersoli that will not accept a 535 grain cartridge in my 45-90 Pedersoli without it hitting hard in the ramp! I was told that my problem was impossible,but it definitely does happen to me. The factory said that a 45-120 would fit without any interferance, but they are totally wrong! And refused to do anything about it!
And that the problem is mine not Pedersoli's, because I didn't tell the Pedersoli factory right away when I first found the problem, that the rifle was out of warranty. The president of Pedersoli was told, and shown, the problem, but refused to do anything about it.
Dick Trenk was my go between on this problem and worked with me to get my problem across to the Pedersoli people, but to no avail.