Keep in mind this is my opinion only, but going from the 357 Max to 45-70 is definitely a jump in recoil. I think 44 mag kicks a little more than the max, and the 45-70 kicks a lot more than the 44. If you use the table hobbyist posted a while back, here are the numbers using 7 or 7.5 lb guns (I know its not the same but you'll get the idea. Also it only had 357 mag and not the max.): Numbers are the round, recoil energy, recoil velocity and the load.
.357 Mag. 4.7 6.6 (158 at 1650)
.44 Mag. 11.2 9.8 (240 at 1760)
.45-70 23.9 14.8 (300 at 1800)
.45-70 18.7 12.7 (405 at 1330)
This doesn't mean that you can't handle it, but it does mean that you will be dealing with more. Some guys do just fine, others can't take as much. I'm in the later class. I've shot hot loads in 45-70 and 375 JDJ and did OK, but I just didn't like it. But you can always load lighter if you need to...