It is just a simple lock
If its just the key you need...any good lock smith can make up keys...either from the number on the assembly or from the assembly itself. If you have it apart to clean...just take it in to the shop. I have done this a few times. The handle is the problem here...I suggest that you buy a spare from Vintage....they are nice and the old one is in a precarious part of its life cycle.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."