Here's the result of my trip to Ottawa. The Canadian Aviation and Space Museum's Np17 is a flyable replica, carefully rebuilt with professional historical input to copy Billy Bishop's machine. The earlier restoration work was tightened up following a smash-up in the late 1980s. Because the aviation museum had loaned the Np17 to the Canadian War Museum,I headed over to the war museum tonight.
I was disappointed to find the aircraft was ceiling-mounted, so a close-up of the instrumentation was impossible to obtain. But I was still able to make some hopefully useful observations. First, the museum had a very enlarged poster of the well-known photo of Bishop in the Nieuport with the Lewis pulled down on the Foster mount. I had suspected that there might be a dark faced instrument on the right side of the cockpit, above where the French tach would be, but that was not clearly visible even in the enlargement. There was, however, a period pitot on the lead edge of the starboard V-strut, so we can assume there was a British airspeed indicator on board.
There was a non-period altimeter mounted on the right side of the windscreen, which we can ignore. In a separate display under glass, there was a bullet-holed Nieuport windscreen Bishop had kept as a trophy, which I photographed. On it was mounted a simple bubble-type bank indicator. It is visible in some period photographs. There were two small pewter-coloured plates on the instrument. The one on the left bore the manufacturer's name over another word, possibly the manufacturer's location. The one one the right bore the letters "w" and "d" for War Department, separated by the War Department arrow symbol.
I realize that you are working to a time restriction, but I will be back in Ottawa in late March and can make appointments to do research in the considerable archives of both museums. Please PM me if there is anything you have a particular interest in.
I will PM you with some other photos I took tonight that may assist future developments.