If you already have 45-70's, I don't know what a 444 would get you. It's about 3/4 the power and essentially the same trajectory. Now the 348 would be something different, so that's the route I'd go. But brass availability is a thing these days and not likely to improve anytime soon.
Took me less than 30 days to find and buy over 500 rounds of new Winchester brass and another 250 once fired Super X. Cost me $400 give or take . Also bought 4 boxes of new factory ammo and 7 vintaqe boxes.
