Why do you want to change the 6N1 tubes? Don’t you like the sound, or something else? As pointed out, it is not a good idea to “roll tubes” of different types if you are not knowledgeable about what you are doing. Also, if you have a schematic please post it - you are likely to get more sensible feedback then.
The best replacement for a 6N1 is a tested (and matched) Russian 6N1P-EV. No other tube type is a good substitute in a circuit that is optimized for 6N1. If the manufacturer stated that 12AU7 and 12AT7 could be substituted the circuit is not optimized for 6N1 alone, but if so specified it should accommodate the 12AU7/12AT7 substitutes. Why do you doubt the manufacturer’s specification?
Please print out the datasheets for 12AU7, 12AT7, 6N1, 6922, ECC85 and 6BQ7 and compare the important parameters. Be careful not to exceed the max plate voltage on a substitute, especially 6922, if you should try it.
Also see:
Substitute for 6N1? 6922 mebbe? | Audiokarma Home Audio Stereo Discussion Forums
Good luck.