This is something I do every year (on Twitter) for what I call the big 8 (Picture, Director, all acting categories, both screenplay categories). But, I'd also be willing to throw it open to all the categories.
For Best Picture, 10 nominees can be submitted (because that's the maximum amount). If a situation happens where, for example, there are only 7 nominees and you correctly guess all of them but still have 3 extra movies, you still will be given 100% for the category.