Keeping angels and smaller fish together tends to be a bad idea, if the angels are fully grown then they most likely will certainly eat the guppies, however it can depend on the nature of the fish, I have 5 angelfish in my tank 4 of which are fully grown, and a smaller one and have been keeping them with cardinal tetras some of which are quite small (have a shoal of about 15 or so), and the angels are fine with them, instead of guppies you may want to try cardinal tetras.. try to get fully matured ones if possible as they will be too big to fit inside the angelfishes mouth.