that's perfect, personally I would keep it at that (or less). Huge men choir voices sound horrible in my opinion especially if they aren't harmonizing. The all male choir I am forming at my church is going to end up only having 8 members. To which they have to try out for.
Here's some songs:
Cooling Water
Fix It Jesus (On my Way Home)
I Recommend Jesus
Mississippi Poorboy
I can go on forever, but those quartet style songs are the most promising!!!