Yup, I made them and have a box of them on the shelf if anyone is interested.
They are a 1/2"-20 thread (AN5) body and several inches of threads. If you have down nozzle heads, they'll screw right in. If not, you can drill and tap through into the intake port. Thread the bodies in tight and grind off the excess brass flush with the port wall. It leaves a .100" hole. They are meant to stay in the head so as not to screw up your flush grinding with the port.
The top portion of the body accepts the standard Enderle-style nozzle jets and you should run an Enderle check-ball setup in them so gravity doesn't fill the cylinders with fuel for you. I do run a 20 PSI spring in them. They are non-aspirated. They could be aspirated with small holes, but would have to come out below the check ball. Not worth it in my opinion.
Spud