Chris,
The .30-30 is simply not a 250 to 300 yard cartridge. It was never intended to be. With a super accurate rifle, and the Hornaday LE rounds, you may be able to stretch it to 200 to 225 yards, but that is it.
This isn't just a matter of how much "power" it has at 250 to 300 yards, its the trajectory of the bullet. The round just isn't flat-shooting enough to reach that far out, unless you are willing to hold a foot high over your target.
As for alternative rounds in lever rifles that will easily shoot 200 to 300 yards, the Savage Model 99 lever can be had in .243 Winchester and .308 Winchester. The Browning Lever Actions (BLR) can be had in just about any centerfire round, including the .243, .308, 7mm-08, .30-06 and 7 Mag.
I believe that Marlin introduced a new cartridge last year (called the .308 Marlin), that they offer in their lever actions, and virtually duplicates the .308 Winchester ballistics (although the ammo would be really expensive.)
For a few years iin the 1970s or 80s, Winchester made its Model 94 lever action in .307 Winchester, but I'm guessing the cost of that ammo is really high as well. It was very close to the .308 in ballistics.
If you are really interested in long range shooting, then you should just get a Savage 99 or a BLR in a .243 or .308, BUT the majority of these would probably not give you better than 2 inch groups at 100 yards FROM A BENCH (meaning 6 inch groups at 300 yards)! Yes, there are exceptions, and some of these rifles will shoot one inch from a bench, but that is certainly not the norm.
Bottom Line: Lever guns are highly valued because they are slick, light, fast handling, quick shooting rifles, providing average to above average accuracy with little maintenance, but they are NOT target rifles.
Regards,
Mannyrock