Re: Reusing head bolts.
 

Boy, I don't know; a head bolt with a 5/8" hex is just wrong in my book!

Re: Reusing head bolts.
 

I found that the torsion value of some of the bolts was exceeded when trying to REMOVE
the bolts from the heads, so even though they weren't stretched I replaced them with Grade 8 zinc dichromate bolts which are much stronger but have a slightly smaller head, so you will have to glue chrome nut covers on if you use them.
Also use hardened S.A.E flat washers under them.