I'll start.
Take your head to a machine shop and have it checked for cracks and if your seats are good. They may need to be ground as well.
Also have them check to see if it is warped and needs resurfacing
Have the machine shop check your guides for excessive wear
Check to make sure your valves can be ground
This a pretty normal list of what is checked before rebuilding. I may have missed some things, and others will probably offer comments.
