You can buy the Time Sert kit. I beleive it is around $350.00 $400.00. I know of a few shops here in Omaha that do the repair for around $250.00 a hole. Still better than a new head. Some people on here have done all 8 holes.
Once fixed that hole should not be problem. Do a search on here for directions on changing the spark plugs. Torque is very important.