I have a .75" warmouth(very similar to greens) that ate a 1.5" fathead minnow. It took him a day and a half to get it all the way down. It wasn't intended for him though. It was originally for my 3" female I'm trying to get big and fat for next spring. Well, I guess where there's a will, there's a way.
i dont see a problem with that. i have 2 sunfish (one pumpkin seed, and one bluegill) and they are awsome no aggression towards any other fish. i think you'll be fine.