I can't say how reliable this strategy is, but it did work on many occasions for me. 65-70% damage in about 12 (in-game) seconds. You must be aggressive and keep him on the defensive. The timing and distance for sweeps is tight. Shin Gouki _loves_ to punish on them when he has a super combo available. This is also proof that you can capitalize on him during a dizzy. Sometimes, he will recover fast enough to transport away, block, or attack. However, if your timing is right, you can score some free hits the overwhelming majority of the time.
1