Regarding the 6N1P.
This tube is not completely compatible with the 6922 family.
It has the same pin out and is a dual triode like the 6922. I believe gain and transconductance are quite similar but, the heater current requirement is not.
This tube requires twice the filment supply (heater current) than the 6922 family. Something like 600mA for the 6N1 vs 350mA for the 6922 family. This is fine if the power supply for the heaters can supply twice the current but, trouble if not.