I just fitted an Edelbrock Victor Manifold to my motor and a 1000CFM 4bbl Throttle body. I picked up this oval air cleaner from Summit Racing that I reckon might work OK. It's an airflow top style but it's narrow enough that it will fit through the scoop opening (after a bit of surgery on the hood).
The air cleaner is about 12" long and 8" or 9" wide with a 2" high element.
Here's the hood scoop opening and you can see where I've got to widen it a bit.
Cheers