I have a couple of 45-70's. I wish one were a 33.
My 1886 is heavy and I can shoot full power loads in it, no problem. My Marlin is very light and full power loads rap my shooting hand pretty good. My brother had a very light 1886 and he didn't care for full power loads in it.
What are your plans for this rifle? How heavy is it? Are you going to mostly cast bullets?
If you are going after deer, both cartridges will work fine. If you are shooting cast loads the 45 would be a step above the 33. If you are going after buffalo or big bear - definitely 45-70.
