Before you resurface the head, carefully clean it and check it for straightness, use a good steel straight edge and some feeler guages. (they're usually pretty straight) If it needs to be resurfaced make sure the machine shop puts a proper finish on it.

Since you have the head off you should replace the valve steem seals, check the wear on the valve guides, clean and inspect the valves, if the seats are not too bad, lap the valves in.

Stefan.