I know it is kind of a pain and time consuming, but regapping your plugs wider would be more ideal.
There is no set gain, but I imagine you could see a few hp/tq across the board, and then again you may see nothing, but it is the 'potential' of leaving power on the board.
There is just no reason to keep them closed that much if your ignition can handle the extra gap and 'jump' the spark...
You will now if you gap it too far because you will get a miss more than likely...
If you are ever bored, give it a shot