Anyone built a 6 pack hood plenum?

My hood is the AAR fiberglass model and it has a massive opening underneath. The opening is not circular like most of the set ups I see people building. I will go check out the AAr base mentioned above. Thought I might try to build a plenum that attatches to the under side of the hood rather than a large base plate that sits on the carb. Im guessing this AAR hood I have is different from the stock model.