Hello again eclipse99, after reading others post to your problem I would add these additional comments. As the others have said if the rebuilder has liability in providing you with a block that doesn't have these issues then I would work that angle and try to get a different engine. If you are stuck with what you have there are a few other things that you could do to help with locating and drilling and tapping this buggered up hole. I would first make a template of the hole pattern of the waterpump out of some 3/8" to 1/2" plate, either clamp the plate to the back of the water pump and drill holes through the pump holes to provide correct hole locations or use transfer punches. Then determine the size of hole that will best work for oversizing the bad hole in the block(this would be the tapping diameter that you would need for using a Keensert, Helicoil, or the threaded bolt), bolt this plate to the front of the block and use this for a drill guide to drill out the bad hole and locate it properly. Whatever you do, if you are tapping in any type of material use a good quality of tap, in many instances you will have better success in tapping in cast iron if you do the tapping or drilling dry without oils or tapping fluids. This is likely a blind hole, so remove the tap every couple of turns or so and blow the chips out before proceeding. Good luck on your project here. Regards, aevald