Just thinking out loud here, I wonder if you sink the head in a large pan of boiling water for about 15 or 20 minutes if that would expand things enough to hammer them out without damaging things???
Mike B
When I was a working man, we would remove shaft bushings from pump casings by heating it with a OA torch or rosebud, depending on the size. The idea was to get as much heat on the bearing as possible in the shortest amount of time, so you did not heat the surrounding area (in this case, the pump casing which was cast iron). The bushing would expand but the casing would not let it expand outward so it would expand inward. Once it cooled down to room temperature the OD of the bushing contracted enough to allow you to press or tap it out. In some cases, I literally removed it by hand.
As HotRod suggested, drilling it out so it is thinner will help that cause. The guide will heat up quicker thereby reducing the heat transfer into the head.
Edit: If you try this method, do not heat the head, only the guide.
