Eggs benediction for a crowd
French Fries suggestion is the easiest by far. You can cook the eggs the day before the event. Then when ready to serve, the reheat takes only 30 seconds in simmering water. Use perforated hotel pans, lower then into simmering water. 30 seconds later pull the pans up and you can have 120 orders staring you in the face if you want. Quickest way that I know of. I used that method to accomodate 1,000 guests at one event.
You can also use the muffin pan method to do them last minute and ready all at once, but plate up or buffet up it will not be as easy nor quick as the above method.
You really can't plate all 120 at the same time. Do you have someone to run the food? Multiple people? Can you send them by table? Is there a certain amount of people by table. I mean everyone has given you solid methods, but you really can't put that many eggs on plates on your own before they get cold or overcooked.