Different sounding 6922's- Best for ARC ref one?

This is a hard question to answer. One, there are lot's of tubes. Two, tubes can sound different in different gear.

Try reading this for some basic info. http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html.

Also, I'd call a tube dealer or 2 and get their opinion.

Bruce at BWS has been very helpful to me and several of my friends. http://www.bws-tube.com/

Good luck. Retubing from stock will change things...