I am just spitballing here Still a new member. But I am pretty sure it would lower the value of the gun if you threaded the barrel. From my reading on classic guns, any modifications that are not period correct ( and sometimes even those ) will tank the value.

I think if you want a handy, suppressed, field gun you would be better getting a modern gun, and modifying that. And there are plenty of modern levers if you really want a lever action.