Diy Valve job

My 1982 Mazda B2000 MA serial 2.0 has valve guides that are installed with a F'n hammer! The FSM shows a guy with a mallet and a drive tool (arbor, ID and shoulder on it) pounding one into the head. These are obviously AL heads made that way but they have drills that center in the old valve guide and drill out for new ones. press in new bronze guides and ream to fit. Old seat cutters were the same, they centered into valve guides and had a flexible drill attachment that allowed then to grind off angle. If you got a set of heads that your not huge into port work or something very labor or cost intensive, give it a shot. I wouldn't practice on some Econo W2's or anything crazy but some throwaway 318's or Mag 5.2's would not be irreplaceable if it went south.