Really, the only time that the head needs to be re-surfaced, is if it is outside specifications. If the head is cleaned of all surface imperfections [old gasket material] & a straight edge is placed along it, just like they show in the manual, you can check with a feeler guage. If it is within the service limit shown in the book, then it is OK to re-use.

The book will also show how to remove the valves & lap them in. It is something that i recomend be done every time a head is pulled. No point in re-installing valves that are half way through a service life. A couple of hours spent here can help to freshen up an engine that is starting to show signs of age & mileage related weariness, & that can only be a good thing.
If the valves are beyond just laping, then you KNOW that the valve job was justified. All shops should do a 3 angle valve job. It's the only way to get the seat within the correct width & position specs.

The workshop manual for your car can be the best investment you can get. Even at say, $50, it needs to be able to save you that much on only one job & it's paid for itself. The best part, ..it never wears out.