Wow, I have never heard of that happening, without a warped surface or stretched head bolts or something and looking like it wasn't torqued down I mean.
It's a crap shoot. I would use new head bolts anyway, maybe ARP's. I have a tendency not to trust the new clicker type torque wrenches. I have seen too many questionable results, even on wheel lugs. I use the old (less accurate) but more reliable beam type.
What ever, I am not an engine builder or even well versed on such issues. Never could afford to build an engine.
Anyway, welcome aboard here and best of luck!
Any chance you could post a few pictures? Sounds like an awesome rig!