Drum to Disc LBJ 1/2" to 9/16"

Have everything ready to change my 64 over to KH disc brakes. Donor brakes came from 68 Barracuda. Since I need to change the Lower Ball Joint to 9/16" from the original 1/2" my question is do I just redrill the hole to 9/16" that the LBJ goes into or is the hole tapered and more complicated for drilling?....Thanks.....Kevin