These are now being made by David Holyoake. I supplied copies of the original drawings and have tested a nozzle, as have others. It looked, measured and performed very well. IMHO they are cheaper and better made than those from the previous supplier.
I have no connection with or financial involvement with David.
Please email me for contact details if interested, and specify the size of engine and preferably the number stamped/etched into the nozzle.