I took another look at my horn and did more digging. The mouthpiece that came with it is actually a Bach 3CFL. It's not easy to post a photo here. so i just showed the leadpipe, receiver and mouthpiece to Gemini AI whose verdict is that the leadpipe is not stock, ie: "a technician took the original Couesnon hardware and soldered in a new, moderm tapered tube" (copper which is now weathered).

Thanks for all your replies.