I have a lead that I am pursuing.
Grated it is a slim lead but I am chasing it none the less.
I am talking to a valve manufacturer, and since I am a design engineer, I am in the process of making up the drawings to have a correct valve made just for us.
It will look very similar to what you are used to and work the same.
At first blush the numbers appear to be feasible for production.
I will know more in about a week.

And yes I just got my first jet that I hope to maiden in 2 weeks, so I need one too.