You can take it in one piece, but you should just read the number on the lock cylinder and call A&L and they will cut you a new key. Then you can have any key cutter duplicate your blank to the new key.
I can post a picture of the number if you need it. What year is the popout? Is it the first style for the oval speedometer instrument panel, or it it the later style, with a steel plate crimped in place on the back of the cylinder? The later style is used with the round speedometer instrument panels.