Are the head bolts stretch to yield or are they reuseable?

Is there a kit that I have not found yet that actually replaces all the engine bolts? I'd prefer stainless. I'm finding kits that have a lot of bolts I don't care about such as oil pan and dist. hold-down.
I'm looking for a "complete" engine kit.

 

SBCs all have reuable bolts. as far as i know all TTY bolts will have a torque spec like 40 ft/lbs and 1/4 turn or 40ft/lbs and 25* more. ARP ought to have all the bolts you want.