If your wanting a traditional style rifle that can kill elk out to 200 yards, that is a challenge. Since your talking traditional I am sure your not talking scope. So that means a very good sight on the rifle. Next you want to throw lead.
Let me point out, long range shooting with open sights is not impossible, but it takes gun skills, good techniques, practice, and finding the right load for the rifle you shoot. Also it takes good eyes. But I am sure you would not be attempting this if you did not have the shooting skills to pull it off. I shoot a lot, but with open sights.. that's too far for me. Even with one of my lead throwing rifles. My eyes just would not permit that.
Are you going to build this rifle or buy it off the rack? While there are some excellent made commercially produced rifles out there, if it were me.. I would be looking for a 50 caliber that could handle big lead conical bullets. Bullets in the 425-500 grain range. Now a large pure lead conical bullet can and will get the job done at 200 yards or less. But to be realistic, that is some long shooting.
If you were looking at an inline rifle I would tell you find an 50 caliber White Model 97, 98, or Super 91 in .504 caliber. And then cast some 460 or larger conical bullets and work up a load with 100 grains of powder. I would feel with a good peep sight, and a lot of practice, that would be a 200 yard elk rifle.
Now a while back, Green Mountain Barrel Company did sell a 50 caliber barrel with a 1-24 twist and a traditional tube style scope I think made by Leatherwood that fit on a T/C Hawkins stock. With that barrel bedded, that would be a 200 yard rifle. Granted, once you found the right conical bullet to shoot. Green Mountain Barrel Company also made some 1-28 twist barrels that shot conical bullets very well. Many of the members purchased them. I own two of them. But I have shot conicals out of them and again.. I am not a long range shooter but they do shoot conical bullets well.
If you were to try and get closer to the elk, say 125 yards or less.. then a 54 caliber roundball or 58 caliber roundball would do the job. Even a 50 would probably, but I would always go bigger to be on the side of caution. These rifles are out there. Lyman makes a fine roundball shooter. Called the Great Plains Rifle. They also make a conical shooter (I own one) called the Great Plains Hunter. It does shoot conical bullets and sabots well. Maybe not to 200 yards in my hands but in a skilled set of hands and good eyes, that all might be possible.
My Great Plains Hunter does shoot powerbelts very well. And I do mean very well. But really, all a powerbelt is to me is an over grown roundball. But a 405 grain powerbelt out of that rifle might get the job done. I never shot any conical that heavy out of mine. So I can not comment on how well it might do. But I have shot a few Hornady Great Plains conicals and it did very well with them out to 50 yards.
So because of the distance you want to shoot. The fact you want to shoot lead. My recommendations would be the White Rifle if you went inline. Traditional style I would look at a Great Plains Hunter in 50 caliber and start testing conical bullets, or the Green Mountain Barrel with the 1-24 conical barrel.
If you want to get closer and still shoot lead... the Great Plains Rifle in .54 caliber or a Green Mountain barrel in 54 or 58 caliber.