Hi, I have an old Screamin' Eagle backing plate that just has the breather holes closed up with small bolts. My external setup is older as well, it's what's usually called a "horseshoe breather." It's pretty simple, and they're still available. I would also check out DK Customs. They offer several nice breather kits. Since the really don't interact with the carb, it doesn't matter which one you run... The trick is how you block off the holes in your backing plate...

I'll point you to some pictures of mine that may show some detail tomorrow...