If you choose to drill the head off, just do it. I've done this once and it didn't hurt the head, but I worried about it.

Do NOT remove the other bolts first, I suggest doing this with all of the other bolts tight so that you don't risk warping the head. If you remove all of the bolts except this one it is much more likely to warp the head, especially if it's an aluminum one.

There will be plenty of bolt shank to grip to extract the bolt once the head is removed, and it will likely turn out by hand.

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Gone to the dark side

- Jeff