I bought a set of locks from Z Car Depot for a 240Z, and they work You might need to turn the tab 180 degrees for one side of the car, but they seem to work just fine.
My issue seems to have stemmed from a spacer/cushion-thing on the arm that actuates the lock from the tumbler. Mine was still soft, but very loose in the mechanism. My passenger side didn't have it at all. Without this part, the key will not be able to turn enough to lock or unlock a door. I'm not sure why they went with this design over a more direct actuation, but it seems to be the root of my issue.
Since I was missing the passenger side and the driver side wasn't working right, I came up with a solution. It is probably only temporary since it's soft rubber, but I took a small vacuum nipple and cut the end off and cut it in half. I slid it over the actuation arm, and it works great. Very direct action on the locks with the keys.
Hopefully this will help someone else who might be having issues with their door locks from the key and by using a more available tumbler from a 240Z, maybe we can keep a few more cars on the road.