I have SBP's HD White Industries freewheel one on my 72t engine sprocket/shift kit. I removed the crank arm with attached freewheel for SBP's suggested maintenance. It's been a few hundred miles on the road. The wheel's five holes are small, so accept small bolts. My bolts are bending slightly. I want to drill these to accept Grade 8 1/4 x 28 bolts. I tried a reamer, files, even cobalt drill bits, but they don't even scratch let alone cut thru the tough steel. The machine shop will drill the holes oversize for $80.....or more. I'd rather DIY. I have a HD Milwaukee 1/2" drill (not cordless), but it's not doing the job. What do I need?