Can't help you with dies (looks like Mr. Lowe has you covered), and I can't help you with brass directly but I can steer you toward Captech (Jamison) brass. They provide parent .25-20 Single Shot brass that is quite good if a bit salty in price. Still in all it's the best source of brass for the Lovell wildcats. I use it to keep my single shot Krag .22 Maximum Lovell fed that I got from Whitey (RIP) a few years ago- and it's excellent quality stuff.