You can use more than one lever at a time, too. It can be either neat looking or just messy, LOL. I don't have any cams for mine yet (other than the one that was on it) so I haven't played with many of the combinations yet.
I do like the black ones, but I love my green one too. (Maybe I need one in each color?)
I think I'm happy enough knowing it's late 50's/early 60's - the actual date isn't really important, just a detail I like to have in my files. Not that the dates listed are 100% accurate anyway, since those are just the serial release dates and not actual manufacturing dates.