You really need a muitimeter / volt meter. Take a reading of the battery (before recovery charging) to determine the voltage of the battery when it was dead.

That would have given you a much better indication of how far it was pushed into the ground.

The low voltage is one thing, but the longer the duration is actually a bigger concern.

At this stage all you can do it charge it and monitor it to see how it does. You can always get it tested to CCA as well.

Edit:
I feel good lead batteries can be resilient, and can handle a couple deep discharges without too much degradation. If I suspect a battery is low I always measure it first and decide what to do. If it is dangerously low, I never crank the engine and put a load on the battery; I have actually internally shorted a battery doing this making it unusable. I have also recovered batteries from very deep discharge with minimal issues, and they go back into service like normal.