Looking at pictures, the piece that opens the dust cover on the 1873 is a notch on the extractor. Don't see a way to attach the dust cover directly to the bolt. Not sure if there would be any other interfering parts, but it would be pretty easy to dummy up an extractor with a notch that manipulates the dust cover in both directions; however, as a permanent item you'd want to heat treat this replacement similar to the original extractor, which is going to be a much more difficult task.
I'd dummy up an extractor that does this first to make sure it actually works.