The gas shunt reg is a great approach. (Reduction has a Zener shunt reg upgrade kit.) The extra gain stage risks being overdriven unless you put a gain control between the last 6922 and the 6H30 grid. A gain trim would allow you to match gains, adn well as optimize them for the rest of the system (see my "signals and noise" paper on the Community page). Put a second output at the same point so you can compare, and decide whether the extra gain and drive makes up for the added stage - that's how the Tape Repro is set up. Different systems have different needs!
