I had an adult pair of bonded females (both bonded when well into middle age/old age. They were such an easy bond and ended up best friends. Equally, I have tried to bond other adult females and they have literally pulled chunks out of each other.
Really it depends on the personalities of the bunnies. You're doing absolutely the right thing by getting them spayed, so well done. If you then wait at least 8 weeks to give the hormones a chance to die down, then you are likely to have the best chance at bonding (although by then we will be in breeding season which may or may not be an added complication).
Make sure between now and then you do a lot of research into bonding. There is some on my website (link in my sig under 'Flash's Place') and there are lots of threads on the forum too which will give you a huge amount of info