Modifying for Rotation

I’m currently encountering a Problem with a chessgame.
The script I’m using (basically C&P from a tutorial) sets the rotation to a quarternion making it non rotated but i need it rotated by 90° on hte X axis to look like a proper chessgame where not all figures are immediatly knocked over. Any help please?

On anymore information that are needed please ask!

Modify this line:

GameObject go = Instantiate(chessPieces[index], position, Quaternion.identity) as GameObject;

like that:

GameObject go = Instantiate(chessPieces[index], position, Quaternion.Euler(90f, 0f, 0f)) as GameObject;