But if you wanted to do what you are thinking. The back to back reveresed gas tubes output the few volts of bias needed. so say one is 149v one 151v you get 2 volts. so the 270ohm cathode resistor in zarithustra would be some how replaced with that few volts. Not sure if this is possible or correct I never experimented with srpp. I'm sure someone on that russian forum could tell you exactly how to do it. they may have already did it.
Why not try ,did myself, single ended gassed 6e5p like in melq for preamp. It can work but nothing interesting to me.
thee srp in Zarathustra is cathode bias, melq is grid bias. If gas biased the srpp it would no longer be the circuit in zarathustra. what would this do to sound i have no idea. The function of the gas tubes in melq are not only for providing bias. Most importantly they absorb garbage and shape the sound. They need to be in the location and circuit to do what they do.