'93 Ford 460 - 2 broken exhaust bolts (pic attached)

I'm confident that if you'll get a hole all the way through, centered, that you will get them out. Once drilled, squirt that Kroil through the hole, tap on the piece, let it soak, THEN drill again using a larger left hand bit. I think the larger left hand bit will back the pieces out before it drills all the way through. In This Set from Amazon pictured here I would want you to drill to 1/4" and use the #4 extractor. Bigger it is, less likely to break it off.

But I don't think it'll come to that. I think your first or second drilling with left hand bits, will get them out.