I think Edelbrock has one available. And Holley may too. Other than that start looking at the street rod sites and publications for Billet versions. If all else fails a decent fab shop can make a base for you and any machine shop can make a lid to your design.
EDIT: Summit has a few different styles, some Hilborn style scoops for single and dual set ups and others. Edelbrock has the Elite style with the raised ribs similar to the Ford style you mentioned. There are a bunch of them on just the Summit site.