It sounds like you need a bigger sump! The best way to test to see if your sujmp will overflow during a power failure is to turn you pump off, fill the tank and watch the level of the sump rise. Once the level of the sumpis at the highest level that you want it, shut off the water. This is level will be the level of the sump with the power off.
Now, if your pump is draining your sump faster than it can return, there are a couple of things that you can do. Try and make the sump bigger. This may help with noise, but may not really solve your problem. Most people that have powerful pumps install a valve on the return side of the pump and then trim down the flow to meet the overflow return rate. The valve in my opinion is the best way to deal with it. Another solution would be to add a second overflow to the tank to speed the return of water. You may still need the valve to make slight adjustments to the flow.
Hope this helps!
Best wishes.