We are working on a Alphacowboy's truck here fixing a blown head gasket. Head is off, machined & oringed ready to go back on. While using a bottom tap on the block stud holes - you guessed it, the tap broke. Of course it is the hole at the very back of the block. It is broken ~1/4" down in the block about even with where the threads start and the tap is/was all the way in/bottomed out when it snapped. He said he is fairly sure it broke when trying to back the tap out so it for sure is in there really tight. We've tried a bunch of homemade tools to fit in the 4 slots of the tap and get a good grip on it but nothing seems to be strong enough to back it out.

Suggestions?

Thanks,
Deon