Last I heard, there was some kind of distribution or ownership rights conflict regarding current Svetlana tubes. In the USA, the tubes that were the originally Svetlana are now sold under the "Winged C" or "Circled C" logo...I believe that current Svetlana tubes are in fact, really Sovtek tubes....at least as of a year or two ago.
I don't know what you have for testing gear, or your experience, but there are many tube suppliers with known reputation, and full tube lines [Yugo, China, Russia] and have access to supplies of NOS tubes as well.
I have no idea of the Custom forms and duty that might have to be considered for such an endeavor. Investigate all aspects CAREFULLY before making a decision!