I live in the city also, so I know what kind of situation you have, but if I were you I wouldn't put the silvers in something that small. They like to run and jump around so they may trample your quail. To me silvers have the dispostion of chickens which means they can be aggresive to small birds and they may even kill them.
However, if you have a fenced in yard they may be allowed to run free if their wings are clipped. These are wonderful birds, but I found something out about them that every newbie should know, they are not afraid of humans! With that being said don't be suprised if they follow you around the aviary or yard, chances are they're just looking for food sience you are their food source. Some males can be agressive, but i've never had a problem with that. I do have one male, (he's my favorite silver), his name is Stanley. He's the sweetest bird I've had, he actually comes to you when you call him.
You made a wise choice to choose silver pheasants for your fist breed, when I first started in this hobby I got ringnecks! My gosh was that a mistake!