yes essex head bolts are fine to reuse. top tip straight from a ford main dealer mechanic at the time, tighten the head bolts at least 15 lb/ft more than (no more than 100lb/ft max' though) the manual says on these engines. this stops them blowing head gaskets and it worked for me on 2 i worked on that kept doing gaskets despite having the heads and block 'faced' on each.
neil.