I'd try a 240-250 grainbullet/sabot combination with about 90 grains of powder.

As far as using wonder wads, do you put them on top of the powder with the ramrod then load the conical? Or do you attach it to the base of the conical then load them together?

The easy way to load a wad is put the bore button into the barrel and push it down with the short starter about two inches. Then load your conical as normal. As the conical is pushed down the bore it catches up to the bore button/wad and it seats the whole works nice and clean onto the powder charge.

Although I have done it both ways..

370 grain maxi balls lubed up in the grooves with bore butter and 70 grains pyrodex. in my new englander it is a deadly combo and accurate. i tried the bore button wads and all they did was make the gun kick like a mule. i say try without.