I prefer the 45-70. Like BT said ammo is not that hard to find especially with the resurgence of the cartridge due to the availibility of new 45-70 rifles. Not so with the 35 Rem. Besides, there is something to be said for a big chunk of lead flying through the air. Since you already have a 30-30 Win, the 35 Rem would offer you a slight advantage, but not as much as the 45-70.