Hi Rainman,
27a - I think the "once" indicates that that spelling of "you" is archaic as in 'it was once but not anymore' and is confirmed by Chambers.
Hi Geeker,
I think Tim has it right, that it's a contraction of a phrase meaning "we're prepared to" = "we would" = ...... reversed/"to go back".
Of course it should be noted that it was only a few minutes ago I was suggesting there was an error in the clue so .........!