When overhauling the cylinder-head, replacing as many of the wear items as possible will simplify the re-assembly and subsequent adjustments required to set up the Valve gear correctly. The most vital items include Valve guides, valves, stem seals, collets and Valve springs.
This will improve performance, reduce oil consumption and help achieve a smooth, quiet running engine.
Other related items you may wish to consider; check that you order the correct quantity of parts: