Keep in mind that drill bits can give you a not perfect hole in roundness. Also we have seen it before in the shop that drills and reamers do no always do what they say on size. Since it is only a one shot deal and you have a lot of time invested in this project. I would not cut corners this close to making it run. Safer to take it to a machine shop and have them bore it.Do you have a specific bit size that I can buy? I'd prefer not to go to a machine shop to get this done as that's gunna be a pain in the ass, and I don't know if there's any nearby.