This motor was NOT made [specifically] for the fiero. Pontiac Motorsports designed it for there professional racing applications. The Pontiac SD4 was in the Fiero pace car, but with a regular SD head, not the 16 valve cosworth head. I know of 1 16 valve head for that engine still availble.
There was a 16 valve Fiero with that engine and head on it. It appeared in Hot Rod (I plan on painting my Fiero the same yellow and black). The wheelie bars were required on that car, and as the engine broke in it produced more and more horsepower until it maxed out close to 500 hp!!
From: Evan Langlois
For more information on the Pontiac Super Duty, get a copy of the GM Performance Catalog.
From: Sketch