or this 69 that belongs to Paul https://www.dropshots.com/jer57747/albums/359955
You would need to rotate the cylinder to get it to release from the locking shaft. Since you have it out this far, just look for a number on the side of the barrel, and take that number to the locksmith to have a new key cut by the code number.
The reason that the inside door panel is warped, is because the body builder never sealed the large access hole with waterproof paper or plastic sheeting. They saved money anyplace that it couldn't be seen. These cars were never intended to be in service beyond 10 years, and then off to the junkyard mortuary. That is why we rarely ever see many clean rust free cars from the 1930's, 1940's, & 1950's. Only in the 1960's, did some of these cars start to be saved for posterity.
that one has the keeper on the tap of the lock. it is latched on the lock with a tab in a hole. from the inside you need to put a small flat blade under it and lift the end up. then slide it off the lock. that keeper is made to assemble not to remove. they are a pain in the butt. once you do a few thousand of them you get the trick down.
not a lot of room to get you hands in there. but they are a snap to assemble.
here are a a couple pictures of the rod fasteners and how they go on and off. I don't have a lock like that one in the junk box but here is how it sets and were you need to lift it out of the hole and the direction you need to slid to get it off the rod
Have a bunch of keys made by this locksmith, and then put the original one that he made away for safe keeping. Consider the one that he just made to be a 1st generation key, and every key that is cut using that key as a pattern, is a 2nd generation key. If you use a 2nd generation key to make additional keys, those keys are 3rd generation keys, and will not work as well as the original or the 2nd generation key. The further out you get, the more error is introduced in the replacement keys. A copy of a copy, of a copy never works as well as the original key. Also, I hope that he gave you the key number so if you should ever need another original key, it can be made from that number.