Lyman Great Plains Hunter, 1:32 twist rate
Any number of other "Hawkin" Style rifles.
You mostly need to look for the right twist rate of the rifling.
Round ball rifles have slow twist rates in the range of 1:70 and 1:66.
Many modern muzzleloaders that are made for shooting conicals have 1:28 twist rates.
Many cheap production rifles have a 1:48 twist as a compromise that supposedly allows you to shoot round balls or conicals.
If you want good accuracy I think it's best to look for a faster twist to shoot full bore conicals.