With contemporary technology? Not a single clue

Rifling the bore would help improve accuracy at the price of a severe penalty to rate of fire; decreasing the windage might help a little and slow you down a little less, but the bullet will still fly in a fairly random manner and still not do too much beyond, say, a couple of hundred yards. Even the jezail, anecdotally renowned for accuracy at what were, by contemporary standards, longish ranges, has to obey the laws of physics.
The only good reason I can see for adding all this panoply of sights to the guns is as a sort of "on the off-chance" measure. Most of the time, the thing's far too inaccurate to make use of them (especially if it's got a dodgy stock design, as in the Tanegashima), but occasionally you might just happen to encounter the right set of circumstances for them to be useful.