Handle has no place for a lock
A swisco rep asked for a picture with the old handle set removed, so I've included it here. He thinks someone put the wrong handle on a long time ago. I need this handle because the house is going up for sale.
I agree. Looking at your door, there's clearly the outline of a different type of handle. Unfortunately, I have no idea what it could be. That's not something we'd be able to know without seeing the original. Can you open the door and show me the shape of the cutout of the original mortise lock? That may help put us on the right path.
Thanks for clarifying! I didn't realize that's what your first photo was showing. That's definitely a problem.
In that case, the only thing I can think to recommend is a surface-mount handle set like our 82-005 or 82-009A. The 82-005 has a hook lock that connects to a keeper you'd install on the frame, while the 82-009A installs on the frame itself. I can't be 100% sure which would be better, if either would even work, but I think they're the only parts we have that could work for you.
If you know who repaired your door in the past, they'd be the people to talk to. I don't know why they didn't just replace the handle with what was on there originally.