The best way to actually measure the bore is with a pin gauge. You don't need the entire set, just a range of sizes relevant to musket calibers or you could take it to your local machine shop. They're very likely to have a full set and can measure the bore for you. With the actual bore size known, then order a sampler of minies from-
https://www.lodgewood.com/Bullets_c_7.html
Get the size for your bore at .001 under measured bore size. There is NO other commercial source for minies that I trust, not Track, nobody. Lodgewood specializes in military arms and they know what it takes for a quality minie. Molds- once you determine what shoots best, then buy the mold. Again, there is nothing in the Lee lineup currently that shoots accurately. In molds, you get what you pay for.
Get some Scheutzen caps or RWS if you can find them. Anything CCI current production are rubbish for accuracy and are designed for blanks. Pressure for them is inconsistent. Your powder is decent but Swiss is probably going to give better results. Lube results tend to vary from gun to gun and you'll have to experiment. I've found the best, most consistent results with a lard concoction but one of my muskets doesn't respond to it.
IF you're anywhere near McKinney, TX, I can put you in touch with an expert who's a long time N-SSA member and a personal friend.