You can check the labels to be sure about the calcium content in the exact ones you have or can buy. Calcium percent is listed on the labels for any chicken food I've seen in the USA.
People argue back and forth about whether the calcium in layer feed will hurt a rooster. Layer won't make him drop dead in a few days or a week, but might cause slow damage that builds up over time and causes problems a few years later. Some people say their roosters each layer for years and do not show any problems, while some other people butcher their roosters often enough it doesn't matter to them.
The thing that makes layer feed different than other feeds is that is has so much more calcium. So hens that are eating layer feed might not need to eat much of the eggshells you offer. Serving the eggshells separately, not mixed into anything, is a good way to let them self-regulate their own calcium. (And if there are always eggshells available, but the hens are choosing not to eat them, you can be fairly sure they are getting enough calcium, so you don't need to go buy any other calcium supplements for them.)