3.5l head repair

[bull5]

Hi, I have to repair a 3.5l with the valve problem (head to be replaced). Looks like that this is a well known problem... Now I would like to get all the needed pieces from rockauto. I would like to get pieces already modified, I don't want that the problem is coming again....

Can you help me?

Secon question: what the diffrenence between a remanufactored head and a brand new head? A lot of sellers sell remanufactored heads.