I have 40 - 3/4" holes to ream out to 1" , they are in 1" plate on a pull scraper. I was going to drill them with a Mag drill , but am nervous about using a annular cutter to recut these holes. Have never tryed this before and thought the only way to accurately drill them , was to put a 3/4 bit ,set the drill then change to 1" drill then repeat. Any advice would be greatly appreciated.