Unless you are shotoing Elk, or bear, or large Wild Boar, there is no reason to be using a conical in your gun. Those barrels come in about a 32 inch length, and it will only burn 90 grains of powder efficiently. Use a RB, and the load that RoundBall has recommended above. He's been shooting that load for years, from a variety of rifles, and he knows those guns.
If you absolutely have to beat your shoulder to death with a 100 or 120 grain powder charge and a 425 grain bullet, then by all means use some kind of OP wad between the powder and the bullet to protect the bottom of the bullet.
By way of comparison, remember that the .50-70 cargridge, which shot a 550 grain bullet, in front of 70 grains of BP killed buffalo all day long with the bullets completely penetrating both sides of the animals. The .45-70 used the same powder charge behind a .458 diameter bullet that weighed 405 grains. It also was famous, and remains famous for its ability to take all manner of game. There were documented accounts of the .45-70 bullet killing three hostile Indians in fire fights, when the three were all in a single file when the gun was fired.
On the other side, there are very few .54 caliber Round ball, which weight 230 grain, or more than 1/2 an oz. recovered from any deer shot with that caliber out to 100 yards. And the RB are a lot cheaper to shoot.