Head bolts?

you are not supposed to reuse head bolts. apparently they are designed to stretch when you torque them down

i'm 95% sure that if you use head studs, you can resue them. the ones i have (arp) screw into the block with an allen wrench. that way you can take them out if you need to the next time you change heads.
 
You can reuse ARP head bolts and ARP studs, the latter more so.

If you were on a serious budget, you could technically use the stock head bolts. They will still clamp, but it isn't recommended.

I have used my ARP head bolts 3 times now. Not worried about them at all.