You can't drill that if you had kryptonite drills. Hardened after machining. If you try , you will screw up the threads. If you take it off and take it to a machinist, they can do it. But you need to find out why it's like that. The kits are not made to have to drill a hole. Aren't the old bearings ball bearings and the new are tapered roller bearings?

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn