As an owner of four '65-'66 T-birds who had the factory option of a leaking exhaust manifold on the driver's side, I can tell you that a broken bolt is never any fun. Especially way down next to the fender well.
I also broke four exhaust bolts on an AMC 304 head I was once rebuilding. I never use E-Z Outs because they usually break in the bolts. Penetrating oil is no guarantee either since I have found most just don't penetrate to get at the rust. Try spraying some on a flat surface and see if it evaporates. If it does it cannot penetrate. So on the AMC head, I just driled out the bolt as suggested usigng progrssively larger bits until I got most of the metal out. Then I ran the correct tap in there and I was back in business. Now AMC was known for a higher nickel content in their castings so that might expailn why this procedure worked so well.
Reverse drill bits are a must and I have a complete set and many times that is all you need.
Later!
Mr. Ed
