If it were mine, a lot depends on how many miles its done. If it was say 50,000 then I would guess something drastic had happened to it like a previous owner having a water leak and seriously overheating it, whereby a skimmed head and bolts etc would be wise. Whereas if it had done say 250,000, its more likely that the gaskets worn out or been eaten away by the anti freeze (or lack of)/combustion gases and whilst the head may still need to be skimmed, the rest may be more salvageable. In any case a new belt, idlers and water pump would be a prudent move, and (as said above) you will need cam/crank locks.