It definitely does work great.

Just don't scrub for too long, or you'll rub off the surface finish.

I buy my PUI upholstery through NPD as they are local for me. However, if you go to the dealer list on the PUI site http://www.pui.cc/ you can find a dealer fairly local to you. Even if they are a Chevy shop, they can order the Pontiac covers for you. Just note the difference between standard and deluxe covers and cushions.

These are probably the best cushions available: http://www.americancushionind.net/categories/firebird.php

And don't forget the seat springs, at least the driver's seat bottom and side springs if nothing else. Once you replace them you'll be amazed.