First you have to know if it's a straight or tappered wall hull. Then you can buy the correct wad - Federal style wads for a straight wall, Win/Rem style for a tapper wall. With the proper style wad and the amount of shot to be used, you can then deciede what powder to buy. Most your standard primers are about the same - at least at the low pressures we reload it won't make a lot of difference. You'll have trouble useing plastic wads in 2 1/2" shells. You'll have to use fiber wads from
www.circlefly.com to get a proper component height for a good crimp. Or, and I'm NOT recommending this to anyone, but what I've done in the past is use a wad intended for 1 1/4 or 1 3/8oz and load 1oz. The only thing that changes is the height of the cushion section of the wad. I have many reloading data manuals from different powder companies and after reviewing the data feel different wads from the same company can be used safely. This is just my feelings and only when useing the low pressure loads I use. If I were loading at the high end of the scale I wouldn't do it. Anyways, good luck and have fun reloading.