Replacement lock

Hi there!

Your mortise lock looks very similar to our  82-218, albeit upside down from how it normally is installed. As for the handle set, is your thumb lever fixed in an offset position or is it centered? If it's in an offset position, you'd want our 82-086 but if it's centered, see our 82-030 instead. Both of these handles have 3-15/16" hole center spacing. Look these over and let me know if you have any questions. 

You also might want to see if the mortise lock inside the door is broken. To check this, remove the handle set and try manually throwing the lock with a slotted screwdriver. If it doesn't throw, then the mortise lock will need to be replaced also.