You did not mention the model of your BAT, but posting that info may allow another member to suggest something proven for that circuit.
Strictly as a guess, I would use RCA black plate 6SN7, Sylvania Mil spec or (best of all) RCA 5692 red base. I would get same tubes, ( all RCA, all Sylvania , all Tung Sol, etc). This is not a difficult tube to find, there is no reason to compromise.
I would not choose the current Russian 6SN7. It is a poor example of current production.