even another carby that could be adapted or if anyone know how you can weld the alloy there made out of.
It wouldn't be original, but almost any horizontally operating carb could probably be adapted.
Anything off say a wartime M20 or 16H would probably fit the bill. With an adapter ?
Or even an amal concentric at a pinch.
There are welding rods that will work on zinc alloy diecastings/mazac/pot metal.
Lumiweld 2000 is the name that comes to mind.
These are a very low temp melting rod that uses a low gas flame, for welding/soldering zinc.
You have to be very very cautious, too much heat and it all goes 'blob'. The weld area vicinity needs to be really clean too.
If there is a fuel passage through the middle of this, this can be a challenge to keep intact and clear and sealed.