Someone started a thread on Pennocks, about these.
The only suggestion I saw for something that could be re-purposed for the Fiero was a Fox Body Mustang.
I don't see any way that could work. IIRC, the edges of the Mustang roof are squared off above the windows, as opposed to the gentle curve of the Fiero.
The seals seemed to be very similar to the ones we are familiar with. They still go around the opening in the frame.
Edit - They guy that was selling the car, years ago, said that the C&C logo was on the panels.