First off, welcome to the forum. It is good to have you here.

As for your White Mountain Carbine with the fast twist it has, it might shoot sabots just fine. As for the suggested load you mentioned. Try the maxiball with 70 grains first. Then if the group is good kick it up to 80 grains. You could also try maxihunters.

There are many new powders out there on the market. One of the more popular is Triple Se7en 2f powder.