There are several possibilities listed at NETCOOKS. Here are 4 that I found with no problem.
http://www.netcooks.com/recipes/Breakfast/Easy.Breakfast.Casserole.html
http://www.netcooks.com/recipes/Breakfast/Sausage.Breakfast.Casserole.html
http://www.netcooks.com/recipes/Breakfast/Broccoli,.Ham,.and.Cheese.Breakfast.Casserole.html
http://www.netcooks.com/recipes/Breakfast/Yummy.Breakfast.Casserole.html
They aren't 'bulked' but that's no big deal. The major thing about putting that together for 60 ppl would be what sort of oven(s) you have available. Large disposable aluminum pans would work nicely but you'd have to have the facilities to handle 'em (and you don't mention what you have). As an alternative, you could be sure to invite JC Superstar, make one 9x12, and hope for the best.