I have an old house with all mortise latches. This includes a bathroom door, which does not have a lock. I would like a doorknob with a regular push-button lock on the inside and can be unlocked with a toothpick from the outside. I can't find any mortise locks like this. I would also settle for a cylinder style lock, but I can't find one that takes a standard doorknob shaft (so I can keep the antigue glass door knob to maintain the style of the house). Any help? Thanks.