For a lever action, I like the Henry in .45.

I also agree that you could go with a muzzle loader in .50.

But I have to say that with what your describing, you could go with just about any decent deer caliber. I hunt an area that could have you taking 50 yard shots, all the way up to 250 yard shots. More often than not, they are just under 100 though. My .30-06 does just fine under 100. I don't see a problem here. Doesn't seem like you really need a new rifle.

Now, if your just looking for an excuse to buy a new one, then I'm on your side!!!!!!!!!