If the "reasonably power aircraft" is capable of "reasonably quick" aileron rolls you can take corrective action until shortly before the nose points 90deg downwards by rolling 180deg to next horizon and pulling out... but obviously the earlier you act the better...
In my experience if you end up slow & inverted & unhappy with the situation the best solution is to lower the nose 20 - 30deg below the horizon, accelerate for a moment and then roll upright again.
maehhh