A kit for converting a key-in-knob lockset to a lever handle operated lock employs the existing cylindrical lock and its associated latch bolt. The conversion apparatus employs a lever handle having a non-circular shank portion which is received in, and thus drives, a resiliently biased coupling device which is interpositioned between the handle and a rose housing affixed to the door. The existing cylindrical lock is supported within the lever handle shank portion by a dummy bible member in such a manner as to prevent forces resulting from operation of the lever handle from damaging the cylindrical lock.