My 300 had been puffing blue/white smoke in the mornings, so I saved me pennies and had a full head rebuild, injector pump & injectors recon... What a machine now! Sounds sweet and smokes a lot less now!
Would recommend doing something similar if you're a bit smokey or have an itchy arse and constantly want to throw cash into the "pit"!

how much to rebuild the head?

85 to replace & seat the new valves, guides, stem seals & do a leak test!! I supplied the parts mind... Thought that was an OK price!