6922s are generally not considered as subs for 12AU7.
there are a LOT of 12AU7 equivalents. here are some:
12AU7 Substitutes: 12AU7A, ECC82, 5814, 5814A, 5814WA, 6189, 6680, CV4003, E82CC, ECC186, ECC802, ECC802S, M8136, 7025#, ECC83#, B749, 6067, 6670, 7730, B329, 5963, 7316, 7489