I finally got my "AIS" custom built cold air/ram air air cleaner. Not cheap, but the closest thing I could get my hands on that looks somewhat correct and flows the capacity of the 500HP engine. Notice the "keep your GM car all GM on it" It has a 6" duct on it. It was nice to get rid of that dime store air cleaner I had on it for sure. I updated some pics at my site and here is one.
My Cadillac 500-CID Site 