i can't answer your question but one thing i have noticed about head bolts- they don't have a shoulder the same size as threads on the end, it is always smaller on the ones i have seem. all standard grade 8 bolts have the larger shoulder the same od as the threaded portion. i thought the head bolts i had seen were grade 5 anyway. have you checked with arp, i think that's the name of the company? you can buy high strenth connecting rod bolts and i thought head bolts. i may be wrong.
