All perfect spy does is show you what you would see if you had a spy look at every city and stack on the map. So once you turn off FOW you should be able to click on an army, and instead of ????? you should see unit names and strengths, and so on.

Removing the ; from the perfect_spy call in the campaign script should do this for you. What I don't know is if you have to start a new campaign to get the effect of the campaign script.