Even back in the twilight of the tube era, Soviet "receiving " tubes had a poor reputation, so I would shy away from NOS tubes from the ex USSR.
The Soviet/ex-Soviet/Russian RF output tubes do seem to be good, though.
When I used to work with a lot of tubes, the best were, in about this order:-
Australian made AWV
RCA
Siemens
Sylvania
Philips
Marconi
Mullard
GEC
Brimar
Real crap was:-
Zaerix, who used tubes sourced from whoever was cheapest--- usually the USSR.
The problem I see with buying "NOS" these days is that some may be factory "seconds" which didn't reach specs, & were probably meant to be destroyed, but in the last days of the business were "acquired"by someone.
Others may prettied up "pulls" from old equipment, which may have been removed because they tested "bad".
The most common fault with "receiving" tubes is heater to cathode leakage, which, judging from all the
circuits with DC heaters on the Internet is rampant with those tubes currently available.
A good indirectly heated tube can be used with ac heaters on all but the most sensitive instrumentation
circuitry.