You have things pretty much figured out. A slow twist would be 1-60", 1-70". Round balls killed many men in battle as well as many game animals. I hunt with a 50 and 54 using round balls. I would get maybe 2 pre-lubed patchs in .010 and maybe .015 or .017. Look up materials on line at Track of the Wolf for all your ML needs. They will have two different ball dia which will dictate which patch you will use. A nice tight combo that loads without breaking your ram rod will be most accurate. Always seat the ball on the 3F black powder firmly not crushing the powder charge, mark your ram rod and load to the mark each and every time. I don't own a 45 cal but would assume a charge of 70 grains should shoot well. Others here may have a better load suggestion. The Lyman rifles are a great hunting rig.