The failure rate of multi-bitch combinations is higher than any other (male/male or male/female). I'm not saying that it never works - in many cases it does, but the risk is very real. I think it does depend on the breed, their personality and most of all age. Bitch fights rarely start before adulthood. Meaning that even if you adopt the older Pap, it will be almost a year and a half before you might see any problems.
Bonding or how well they get along before they hit the 2 yr mark is not a factor in knowing if they will continue to get along. This is not a puppy thing and very much a mature adult thing. And if they start fighting, it's extremely difficult to get them to quit. Bitch fights are notoriously about taking out the other bitch. Unlike dogs who generally just fight for rank and cool down once that's sorted out, bitches don't give a d*mn about who's the boss. They're fighting to kill the other bitch. You break up one fight, they'll have another one tomorrow and again next week, and next month. Unfortunately, that is the real heartbreaker about bitch fighting...if it gets to that point, usually your only options are either rehoming one of them or rearranging your home so that they are seperate at all times.
Like I said before, it's not a given, but it is a risk you definitely need to consider.