be aware that when using a reamer in any drilled hole, the reamer , no matter how it's modified, will follow the hole as drilled. if the drill wanders, so will the reamer. an end mill or boring the hole is the only way i know of to straighten up a mis-drilled hole. and being a long, deep passage, a tube repair is about the only thing you can do to fix the block in question unless it's possible to weld an iron patch of sorts over the pinhole. and that, i believe, would almost be impossible to pull off. just my opinion.