I checked 5 dealers and only one listed it as an option and had no stock, not to mention their price of upwards of $700 per tube for NOS AD1s.
What I'm getting at is that it costs less than that to retube the entire Menace with good NOS stock and if you want to you can spend less than $100 on the 5 tubes for it and still get very good performance. No disrespect to Craig, I like his work a lot, but designing a new production amp, even if it's a limited run, around what appears to be one of the more esoteric tubes out there seems crazy.