Tom - if you can, find and purchase a Sharps ladder rear sight. It matches well for hunting, with a silver blade front sight.

I've posted a picture of the sight I'm referring to which is on my Sharps. The Winchester m86 rear sight is very similar. They are available as reproductions, I know, but cannot remember where I saw them - actually bought one at one time and had it on my M94 Colt- which I sold.

I was just today, looking at a friend's new Pedesoli Rolling Block in .45/90. It has the same nasty sight at yours I'd think.
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