302 turbo

Usually called a carb hat. Good luck finding one; they are usually custom made. I would talk to the folks at Paxton about buying one of their carb enclosures. They look pretty good, and enclose the entire carb. That way you can run a standard off the shelf carb. If you use a hat, you'll need a specially tuned carb.

The purpose of the carb enclosure is to have equal air pressure on both outside and inside the carb, otherwise the boost pressure would blow out the fuel. He should also use a boost referenced fuel pump. They can be purchased with the fitting hole already drilled and tapped.