You could always rechamber an existing 30-30 to .307 or 35Rem to .356.
The conversions are cheap enough at around $100, and both of these cartridges are good to at least 250 yards and more.
It is true though, that leverguns for the most part, were always supposed to be brush guns, but Savage, Browning, and Winchester have all put out leverguns capable of longer cartridges utilizing spitzer type bullets which give them the reach you are looking for.
If you think about it, aside from the fun of getting in close, if you are indeed hunting long, a brush gun isn't the answer anyway.
Ranger