fact is you may get away with the old bolts but if it goes again its a new headset,fluids etc to redo it.
you can check the head for being true though i personnaly would always skim unless CR is an issue
there are ground holes in the head telling you how deep you can go with the skiming also if you run your fingers down the bolts and feel a fin bit somewere near the botom normaly they are goosed but if not there ok to use again my dad has done countless head gaskets on fire engines over the last 35 years and never had a single problem using the old bolts again