That's something only you can know. So, this is what I think - but not what is necessarily best.
Plain wood - Sharps are working rifles, not show pieces. There were some fancy ones, but their fame was made in the mud and dust and back of a hide wagon.
Bone case colors - because that's how they should be.
Sights. A very tricky thing on a hunting rifle. if your eyes are good, then barrel sights might be all you need. Or you could put a vernier transition tang sight on it, and use that for 200 yds and leave the barrel sights for 100. I do this with an original Ballard rifle (and a few others as well). Which tang sight, is important. How are your eyes?
My one piece of vanity with my Sharps is a bolt-on pistol grip. Shiloh makes them from ebony and I think they are sexy as hell and functional as well. But I made mine Left) myself from desert ironwood, the other is Shilohs. A little sleeker. This is FAR more functional than a pistol gripped Sharps like the #1 Long Range Express because the grip on that is way too far back to be useful.
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I don't have a lot of other Sharps pictures. This one is .45-100. Way too much of a good thing. But I didn't know. It has a Standard weight 1/2 octagon, 32". I wish it was more like 28" The weight loss would be nice, but it's not super heavy (~10.5 lb). I've killed elk, antelope, and mule deer with it. Then I took it to Africa and killed Eland, Springbok, Warthog, Gemsbok, and Hartebeast with it.
It's a fine rifle.
Back when I had hair, a quarter century back. 260 yds. My longest big game kill ever.
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Eventually, I learned to keep myself out of pictures. But it's what I've got.