I think it would depend on the doe and how much her hormones affect her behaviour (and also how long ago the buck was neutered obviously). Some of my unspayed does in the past showed no hormonal behaviour and would/did take boys easily. Others, you'd be lucky for the boy to come out all in one piece.
Do you know how this girlie would be?
Definitely worth speaking to a rescue about it as rules are generally no spay no bunny but often rules can be bent to avoid having single bunnies if there are strong reasons that a rule cannot be followed. Maybe there is someone on here who is near that could help.