I have both the Miroku/Winchester '73 short rifle and the 24-inch barreled rifle in .44/40. (Don't ask me how this happened.) While I never intended to keep the factory sights on either rifle, I did fire them both with my standard black powder handloads before changing the sights out. I also found the factory front sight to be far too high.
As the rifles are already drilled and tapped for tang rear sights, I put such on both. On the short rifle, I installed the Montana Vintage Arms (MVA) reproduction of the Marble's "Combination" tang sight and the MVA reproduction of the Beach combination front sight. This sight combination has worked out well for the short rifle.
Things got a bit more complicated with the full-length rifle. I wanted that rifle to be configured for lever-action match shooting, so I installed an MVA Beach combination front sight and an MVA Vernier tang sight base. (I believe the Miroku/Browning/Winchester mounting holes are all the same in spacing for all their lever action and single-shot rifles. In any case, MVA immediately provided the correct base.) I happened to have a disused MVA #133 sight staff on hand--their most basic Vernier sight--which has no screw elevation adjustment, and no windage adjustment at all. While this arrangement might work well for some applications, it didn't work out at all for my purposes. Precision adjustment of the rear sight under match conditions proved hopeless. I had to "graduate" to an MVA #130 tang sight staff, which has both screw elevation and windage adjustments. The new staff fit the already-installed MVA tang base, of course. That sight combination proved much better, and I recently turned in a couple of pretty creditable scores (for me) at two lever-action rifle matches. There was still some room for improvement, however, as my aging eyes were having difficulty seeing the MVA Beach sight's standard front pinhead. I therefore just replaced the Beach sight on this rifle with a Baldwin front globe sight, to which I am accustomed on my single-shot rifles. That combination ought to work out better for me, personally, but better eyes could probably do just fine with the Beach front sight.
On both rifles, I chose to fill the empty barrel sight dovetail with current production Marble's Number 95 folding sights. These are inexpensive, and they do work. The Marble's Number 95 originally appeared in 1905, so the sight would be more or less historically correct on a Winchester '73. To me, at least, it always seemed to make more sense to fill the empty barrel dovetail with an auxiliary sight rather than a plain dovetail filler.
Some general information and advice: The front sight dovetail for both my rifles is .393-inch. I'm not at all a gunsmith, but I found a Brownell's fine-toothed dovetail slot file to be a very wise investment, especially after watching a well-meaning but ham-fisted gunsmith bash the forend wood on one of my rifles with a steel hammer while trying to drive in a barrel sight. In any case, I found the front and barrel sight dovetails on both rifles to be slightly burred. Using the dovetail file judiciously, I removed just enough metal from the dovetail slots' interior surfaces to take off most of the blue to make the burrs disappear. Doing the same to the bottoms of the MVA Beach and Marble's #95 sights' bases resulted in a perfect fit.
And, yes, I have gone to using black powder in both .44/40 rifles and revolvers. The use of Accurate Arms bullet moulds of the "big lube" configuration was the key to sustained accuracy. Doubtless, "Dick Dastardly's" "big lube" bullets would work equally well. But that is another matter, and has been well covered in the past by "44WCF."
Hold Center,
Don Kenna