[Amps] Replacement tube for 4-1000a

[Dennis Goebel]

I have found it increasingly difficult to locate good 4-1000a tubes. Just wondering what would be a good replacement tetrode for the 4-1000a in grid driven service. Not grounded grid.
Obviously it doesn't have to be the same socket or filament voltage as the 4-1000a.
It would be nice to come close to some of the other parameters so recreation of the entire amp wouldn't be needed.
I have thought of the russian GS-23 or GU-74 series tetrodes. Or home grown variety like 4CX1000 or the like. Most of these have pretty wimpy g1 and g2 parameters compared though.
Anyway I would like to get some opinions from the experts on the reflector.
thanks
Dennis