That's a lot of rifle !!My last Lever action rifle buy is a Marlin .444.
I have the Henry Repeating Firearms M1 (2nd year production model) in .22LRWin 9422 slicker than wd40, Excellent condition Savage 99H carbine in 30/30 and Marlin 94s in .41 Mag.
I like to use separate levels like these, they can be changed out without having to touch the scope mounting rings if need be, and they come in all sizes and prices...The Marlin uses a flat scope base, various makers. The scope rings to fit the base, with a level bubble in the rear ring are available form various makers. If you buy a set of vertical split rings, you might find a level replacement vile that will fit the split. However, the 45-70 might well produce enough recoil to make any type of adhesive applied to the level vile a non functioning add on. I had a level for years on my scoped XP-100 that I shot in competition, this was before the level built in rings were avalible, it worked OK, but eventually the super glue let go and it went sailing, during a match, of course.
Even though more expensive, I would go with the level bubble built into rings.