Thank you both very much! Yes, it sounds like "at sixes and sevens" would be okay to use. Heather, I had also noticed the tendency for women to confine their gambling to cards, and had assumed that dicing (even the name sounds a little salacious, doesn't it?) would be associated with high betting and insalubrious atmospheres, where ladies did not venture. But it does sound like the idiomatic meaning was sufficiently well established by the early 1800s that I could use it, so I think I will. (I do realize that plenty of ladies had no difficulty playing very high indeed at cards without ever going near a gaming hell, but I can't help but feel it's the sort of thing that a virtuous lady would disapprove, and a gentleman eager to retain her approbation would avoid alluding to in her presence).
Also, I apologize for the title. I meant "at sea" but I've had some fairly substantial loading problems with the site the last few days. It seems to be resolved now.
Also, I apologize for the title. I meant "at sea" but I've had some fairly substantial loading problems with the site the last few days. It seems to be resolved now.