The .32-20 was a favorite of the late Skeeter Skelton, who wrote for Shooting Times until his death. If you can get hold of the memorial issue they put out with his most popular articles, you will find a world of good loading info there. He also had some pretty hot loads published (then pulled) for the .32 Mag... but they were for the smaller Single Six frame. They should be the Cat's Meow in your Blackhawk.
Of course, the best solution would be to sell me the whole mess, since I sold mine in a period of financial embarassment and have regretted its loss ever since.
Froggie