Stereo5,
From Dick Olsher's 2016 review of the AI L3A:
Then, in the mid-1980s, Art discovered the Russian 6H23n-EB, really a premium version of the 6922. Not only is it a good-sounding triode, but it also happens to be rugged, exceptionally linear, low in microphonics, and, according to Art, very stable in his zero-feedback tube designs. Subsequently, all of AI’s Series 3 preamps since 1989 have this Russian tube installed in the linestage. Note that AI no longer recommends Russian-branded (e.g., Sovtek) 6922s due to poor quality control. AI will continue to use NOS Russian-military 6H23n-EB tubes until AI’s Russian distributor can no longer supply them, at which time Art says he will probably switch to the Russian 6H30 tube.
My point being the AI's stock tubes appear to be the ones you mention as having to use.