The six-inch Green River butcher is a good, practical knife that will serve you well. However, the handle scales would have been fastened with pins rather than rivets during the specified timeframe. There were some other subtle differences, but the pins are the most obvious. The makers name stamped or struck into the steel on the early knives (as opposed to being etched) is another.
I agree with
@Red Owl (above). The six-inch John Nowill butcher is about the closest fully functional production made knife you will find for an 1820-1840 impression. It isn’t perfect but it’s close enough. These are made in Britain by a firm that has been making knives since the 18th century. The handle is pinned and the maker’s name is struck into the blade. The steel is comparable to the Dexter/Russell Green River blades, and it will fit the same sheath. Relatively few American dealers sell the John Nowill knives, but there is usually a seller on EBay who has them. I bought one off EBay a couple of years ago for about $25. The transaction was smooth and I am very happy with the knife.
if you can afford it, you might as well get one of the Nowill butchers as a companion for your Green River. They will fit the same sheath. Sharpen them both and carry the one you like. Leave the other one in your kitchen. If your wife cooks, she will love it.
Notchy Bob