I am going through the same problems with my BME 50. I have not found a reamer large enough (7/16") that will do it. This website
http://www.bennettbuilt.com/ has a stepped drill bit in the correct size for around 15 bucks. It has a 1/4" step in it so it guides itself through the stock hole of the prop. Make sure you use a drill press!
Good Luck.