I don't have access to one thats the rite size. The housing is aluminum, so its pretty soft. I hope to get a chance to work on it over the weekend and i can measure just how much wear is there.The expading reamer method may do the job but would not be my preffered method. Do you have access to one in the correct size and with a pilot? Make sure the cutting edges of the blades are sharp otherwise it mess up the hole. Even with a pilot you can still have problems keeping the bores in line with each other so be carefull. What material is the housing made from?