Good luck with the Grade 8 bolts. You'll strip the threads in the cylinder head before you get enough torque on them to keep them from loosening up and falling out. GM used Grade 5 in those locations. As soon as it gets daylight in the morning I'll be glad to measure some bolt length for you on several of the engines I've got stockpiled.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!