Powell made guns with lift-up toplevers from 1864 if I remember correctly.
I have been using a 16-bore version, also a bar-in-wood, by WS Reilly of Birmingham. This also has loaded indicators in the shape of brass rods prodruding through the fences, pushed up by extrusions from the breech face, which come into contact with the heads of the cartridges, when the gun is closed.
The gun weighs 7lbs and shoots very nicely with no flexing in hand or bar felt upon discharge and little felt recoil. I shot it in the british side by side championship this summer hand have used it with some success on walked-up and driven pheasants.
The downside of the design is that when loading fast with cold, wet hands in the field, the thumb is liable to slip when pushing up the lever and you skin the back of it on the sharp angles of teh hammers.
With use, the lever can get quite tight and it requires a lot ofeffort to open. When clean it works fine. Interesting practical points that perhaps help to explain why the top-lever and Scott spindle took over in general favour.
