Looking just fine, Tom. Some of the guys with 20 bore muzzleloaders used to stuff 2 or 3 .54 ca. round balls inside a wad for deer and moose. Others merely used one or two .58 round balls inside a wad.

2 .570s would weigh around 530gr. If they are less than snug inside the wad (inside the bore), an acetate sheet can be wrapped around them. It will fly off with the wad as they leave the muzzle. Cloth patching will also take up a bit of room. Deer secum well to .54 and .58 round balls.