Chris;

I seem to recall we had a similar thread some time ago...you might also try the search function...

I presume since you mention head removal, that the bolt broke as a result of thread-binding upon loosening (in which case, too bad for [maybe shame on] you, for not noticing the mega torque required, and keeping turning without lubing until it broke!)

It sounds like you're doing the right thing, drilling for an Easy-Out of the appropriate size...and to go along with that: LUBE, LUBE, LUBE,...this sure sounds like a job for PB Blaster! You may also want to go in the tightening direction just a little to help the ingress of lube. I recommend against those (Sears?) lefthanded drill/bolt-remover combination deals...as far as I'm concerned they are a gimmick with which you loose the careful control that you have when doing each step seperately...

I suggest you chase the threads (and blow out the hole) before reassembly, use anti-seize and oiled bolt torque values. See: http://sw-em.com/anti_seize.htm

Good Luck