Kirban sells a kit with the correct screws.
They are also available at some hardware stores. Lowe's keeps them in stock, but they are slightly longer than the originals, not a problem though. Otherwise, they are exactly the same.
like someone else said, those screws are very common on GM behicles. GM used different lengths with the same thread pitch, head and washer size under the hood and in the interior of most GM vehicles spanning at least 15 years.
HTH