It would be a bit overstocked, but if you go with a bare bottom tank, with overfiltration you should get by fine. The guppys & corys occupy different levels, so they wouldn't be a bother to each other. Get some floating plants, cheap plastic works fine for a breeding tank, and gives the feeder fry a place to hide. This is not overstocked by breeding standards, as long as it's a bare tank with large weekly water changes.
If you feed heavily, as most breeders do, the corys are bound to spawn. Don't feed cory fry, as they have spines, being catfish, and can lodge in a cichlids throat or further down the digestive system.
I have a 10 set up similar, one less cory, a lot more platys.