If it was easy everyone would do it......

I know you're supposed to pull the head but I didn't. Made the mistake of trying to run a bolt extracter and broke it off inside too, went to a carbide bit and finally got it. I went to HF and picked up a 90 degree adapter for my drill and drilled and tapped for a new one, installed with red loctite. Also pumped up my cooling system with a coolant leak tester to flush out any drillings as I went along. BTW Remflex exhaust gasket and you won't regret it. Best of luck.