The Marlin 1894 action, for handgun calibers, is a different design than the Narlin 336/1895 action for .30‐30, .45‐70, and other rifle calibers. The 336 is a stronger action where the bolt locks up in the front, while the 1894 actions have a rear 'crossbolt' that rises to intercept cuts in and lock the breechbolt.
The 1894 is a shorter action and is better suited for short cartridges. Forgetting the strength of the action, it would be impossible to have these actions feed .45‐70 or .30‐30 loaded cartridges... the action is too short.
Steel costs money, and firearms designers won't waste it. When Winchester redesigned the Model 70 in the early 1960s they went from an '06-length action that would feed .308-length cartridges and that could be modified to feed .375 H&H cartridges to two action lengths: short for .308 and .223‐length cartridges, and magnum for '06 and full-length magnum cartridges. The short actions were more popular and saved steel, the longer actions didn't need special machining for full-length magnums. Plus, the switch away from the Mauser-like CRF extractor simplified machiningvand assembly.
If you want a .45‐70 lever action, the Marlin 1895 is the correct choice. I you have any 1794 and want to switch calibers, trading it in on an 1895 is the only viable choice.