50 to 60 grains of FFg blackpowder, a nitro card, a fiber cushion wad, 1oz of shot, and an overshot card should do you very nicely. You can obtain the wads and cards from
http://www.circlefly.com

If you're not sure of the chamber length, trim 1/4 inch off the shell and do a roll crimp. Actually, I don't even roll crimp, just use an old Lee crimp starter tool.