Well, she's all done:
I ended up going with this lock:
http://www.vandykes.com/product/206580/49891 which is the smallest and pretty much the only left handed cabinet lock I could find. The problem is the damn thing is only lockable when the key is in it. So much for security! I also think leaving the key in is ugly as hell. I emailed the people I bought the lock from to see if there is some setting or way I can key change the key & lock position. Maybe someone here who is smarter than I can help.
The cabinet survived being dragged back and forth to the shop many times and shipped across the country to my new home, California, with only minor injuries. I'm really happy with how it turned out and I hope she maintains humidity. I'm optimistic based on the "whoosh" sound the door makes when I close it.
Now all I need are custom drawers from mad_sv, I can't decide whether I want the full top half covered in a 3 drawer system or if I should only 2 do and leave space for 1-2 more boxes, and to find a decent key hold cover to cover up the gnarly mess where the key is now.