The bolts are clutch heads and the tools to remove them are available from McMaster-Carr and any of the Chevy truck parts vendors. There are three good tech tips on working with the hood and springs. The hood if set up correctly and with good springs does not need a prop.

http://www.stovebolt.com/techtips/hoodspring.html
http://www.stovebolt.com/techtips/hood_lock.html
http://www.stovebolt.com/techtips/bodywork/ad_hood_alignment.html