I will suggest that you first research if your pre is OK with 6dj8's VS 6922's.
If it runs the tubes (6922's) hard 6dj8's will not last as long.
If it runs the 6922's harder you will need Russian/Soviet/Eastern European 6922 equivalents and/or 7308's.
Some of the Russian tubes mentioned seem to be the currently available non EV/EB types (which are not the long life versions like the EB/EV's).
For example - well testing/long life EB/EV versions of the Rocket/Voskhod 6922 types have not been readily available on the market for the past 5-10 years).
I agree with the Brent Jesse recommendation as he seems to have a current stock of reasonably priced Amperex 6922 types, though assume that he is swamped as of lately.
This (reasonable prices) may/will change in the very near future.
DeKay