• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Russian Tube ID

I think it will still be cut-and-try for for screen voltage and cathode bias resistors. I have a pair of Electra-Print headphone output transformers that Jack reluctantly made for me. A lot will depend on how those transformers measure out. I plan to throw them on the bench and find out some time soon.
As both pentodes on the package are rather slippery in terms of transconductance, compensation of the inner loop might prove problematic.