The reason I am asking is because I can't buy the length I need off the shelfThere is nothing wrong with the OE studs; considerably less expensive to purchase a new set, saves a ton of time, however if you are bent on making you own you may want to visit this link:
https://www.arp-bolts.com/p/technical.php
A bit of history and a view of what ARP is making high stress engine fasteners out of.
Best wishes
Yes I see what you are saying, were the threads rolled on the original studs would you know?I would advise not to cut the threads with a die, thought you might get away with it. you would be better of getting the threads rolled, which involves no cutting like a die cut and is stronger.
High tensile steel rod is available off the shelf of most metal supply merchants – thought some will only supply by the metre.