Recently I worked up loads for two Jukar .45s for a friend and one for 4H. One, a very old CVA Kentucky, liked 45 grains of 3F, .440 ball and .015 patch the best. The other, a plains style import from the early '80s, ended up liking 40 grains 3F with the same patch and ball as the Kentucky. Both will keep all balls in less than an inch at 25 yards.
That is what these rifles liked. Yours may be different but a good place to start is 40 grains 3F or Pyrodex P, a .440 ball and .015 ticking patch. Try different patching and ball sizes to see what it will shoot the best.