It sounds like fate to me.
Why should it be too soon after losing Fudge? If she makes you and the family happy, and you can offer her a good home, then it sounds right to me.
When we adopted Max, it really was the worst possible time for us. The house had just been re-wired, the plumbing was half out and we've still (5 months later) got a dis-assembled kitchen taking up the lounge. He slobbers all over the walls and we've had to totally change our plans for the downstairs of the house because of that and his constant moulting. BUT he needed a home, we thought he was lovely and I've never had a more soppy or loving dog (or stupid!). While it may not have been the right time for us, it was the right time for him and we've never wanted to go back on our decision.
I know that the circumstances are different for you, but the timing for Rubie sounds about the same. My only concern would be what to do if she is still aggressive with strangers. Can you cope with that? If not, you may need to give her up, but even then at least you will have tried to avoid her being sent to a home.
Go for it.
Further to your comment regarding your kids wanting a Saint.
If you think that makes him look big, take a look at this one! Not to mention, in the films, the slobber is always clear looking, in real life it's a disgusting brownish muck with dog hair and food mixed in!
OK, the wife is only 4 foot 11, but it gives you an idea how big he is. To put him in context, nose to tail, he's well over 2 metres!