I think I'd go with 8-10 congos & 15 black neons. Or skip the neons & just go with 12 congos.
The "usual" way to get a pair is to get 6 young fish & see what pair(s) might form. You do know almost no eggs or fry will survive a community tank right? It's still fun to watch. Then see what happens with the "extra" angels. With enough decor to break up territories/sight lines you might be able to keep them all together, your tank is bigger than mine was.
The "usual" way to get a pair is to get 6 young fish & see what pair(s) might form. You do know almost no eggs or fry will survive a community tank right? It's still fun to watch. Then see what happens with the "extra" angels. With enough decor to break up territories/sight lines you might be able to keep them all together, your tank is bigger than mine was.