If there is any part of the bolt above the surface of the head you can use an arc or wire feed welder to weld an oversize nut to the end of the bolt ant turn it out with a socket. If none is sticking up then you can put a washer over the bolt with a nut on top of it. You can then weld the nut and bolt together and turn it out.

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Paul
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retired mechanic after 35 years
specialized in Holley carbs and Ford Automatic Transmissions